For almost two weeks now DS is refusing to eat more than a few bites at each meal. This started the day after his well baby appt when we found out he had only gained 8.5 oz in 3 months he is 16 months and weighs 19 lbs 11 oz as of his visit. We were encouraged to try Pediasure, Carnation Instant Breakfast, and high calorie foods. DS does not drink a lot either and won't drink the Pediasure or instant breakfast. We have tried multiple flavors. He is even refusing yogurt now which he has always eaten. He had a couple of days during this time when he ate well but it didn't last. He does have a cold and may be cutting teeth but this has never affected his appetite like this before.
We were referred to a feeding specialist but she is booked until June. We had blood work done and it was all normal. DS is most interested in flinging food everywhere. We try to let him use utensils sometimes but it's a big mess.
I am so anxious about this food refusal that I think I'm making myself sick headaches and I feel like I'm going to cry all the time and a lot of times I do. I'm not looking for advice so much as perhaps other experiences with something similar? DS is developing fine and has always been small but I'm so obsessed with worry about this it's hard to focus on anything else.

Re: Why won't he eat?
Oh, I'm sorry for your frustration and that LO won't eat...but I'm sure he is just a small baby like one of my friend's. He also doesn't really like to eat or drink.
I have noticed that DS is starting to gain weight much slower now too, but he was gaining a pound each month and is 12 months old and weighs 23.5 pounds so I am not really worried! I was also worried about how slow he seemed to be getting in height, but he has finally reached 30 inches tall so I'm starting to try to relax. He just started walking too so he'll probably gain weight even slower with all the exercise.
Best of luck to you and your LO! Remember that every child and human is different.
But about the not eating, I presume he's getting molars or incisors? These are usually waaaay worse than the previous ones : is he following the growth curve? Even if it is below the curve? My DD is a bit bigger but she only gained 8 ounces between 12 aand 15 months and there was no talk at all that it wasn't sufficient. If he actually stopped gaining weight or began losing I could see, but that's not the case...
If you take a step back and look at the big picture what does your gut tell you?TThat's really important to take into consideration... and remember too that these things change so so quickly and we move onto a new challenge... hope that helps some
Baby 2 EDD 7-18-14
I know that he can probably sense my stress so I try to be nonchalant but it's hard. He is keeping with his growth curve though has flattened out a little with weight. He is 30.75 inches tall.
Never did I imagine when I became a mom that I would have so many problems getting my child to eat!
I am going through something similar right now. LO got a nasty cold on Monday and almost immediately stopped wanting to eat, and now is even starting to refuse her bottles. She actually lost 1/4 lbs this week (luckily she's a chunk and has some to spare, though I'm still not happy about it). I try to offer food fairly often, not to let it phase me when she throws things everywhere, and to try and offer variety. It's really hard, I know! Colds have never affected her appetite like this before, but they always affect mine. I assume this cold is just worse than previous ones as far as post-nasal drip and that's making her stomach feel not so great. It is super frustrating. I'm going to give it another few days and if she's still not eating on Monday I'll call the doc again. No real advice, just to let you know you're not alone!
Hope your LO feels better soon!
Married DH 7/30/11
CSC arrived 5/7/12
CHC arrived 6/2/14
DS went on an eating strike around that age. He would only willingly eat yogurt, cheese, fruit, and bread. Anything else was a huge struggle. I read in a book that their appetites adjust around that time because they don't need to gain weight as quickly. I don't know if that applies in your case since your DS gained so little.
The worst part of DS's eating strike lasted about a month, but he wasn't really back to eating "normally" for about two or two and a half months.
Keep offering food. Set aside enough time to sit and try to get him to eat. Try bribes -- I would give DS a few blueberries after he took a bite of whatever protein I was trying to get him to eat. (He still fussed, but it worked.) He is also more likely to eat things if he can dip them in ketchup or applesauce (yuck...).
Just don't give up on offering a good variety of food, and encourage him to take at least a bite of whatever it is.
Also, it wouldn't hurt to make an appointment with the feeding specialist.
Edit: teething also made the eating strike worse, so I wouldn't rule that out.
LOs go through times when they eat more/less depending on a whole variety of things from growth spurts, teething, mood, etc. Keep in mind, kids have very small tummies, so a few bites may be filling him up. My LO is big, and he only will eat small amounts, sometimes just one or two bites and he's done. Outside of malnutrition/neglect, kids growth is largely genetically predetermined. If you're offering him a variety of healthy foods, he will eat a balanced diet and enough for him. Just like some adults eat more/less, kids are the same.
You mentioned his weight but not his height, always seemed like my kid would put on weight, then grow an inch overnight, then not change for weeks. Baring weight loss, if his overall growth/health/development is good then I wouldn't get too worried about his size.
Sometimes people (Drs included) seem to only think time kids are healthy is if they are above 50th percentile. But that's not possible, and growth charts are made by taking the measurements of healthy children. So anywhere on the chart is still normal. So say LO is in the 5th percentile, that means he is bigger than 5% of kids his age and while he's small, he's still perfectly healthy. While comparing kids size to others of the same age can be useful, it's only one small piece in assessing child's health and development.
IME trying to "force" kids to eat more never goes well and just ends up being more stressful for everyone. It sounds like you are really stressed out about this, and I hope this helps you feel a little better. Good luck!