This is probably a stretch but I am hoping to find someone that has some experience with what we are going through. Here goes...
My son who is 20 months, has always been underweight (currently 21lbs) and has had a vomiting problem since we started him on solids. At our 18 mo check up our Pedi suggested we see a GI doctor for his persistent vomiting and inability to gain weight. He has gained about 1.5lbs in the last 10 months and has also stopped growing longer/taller, he's 31 inches now. We took him to a GI yesterday and we are waiting for someone to call us to schedule a number of tests and xrays to see if they can find what is wrong with him. They are throwing around words like EoE, celiac, food allergies, GERD, inability to thrive and it is completely freaking me out. We also have never been able to sleep train him because if he cries too intensely for more than a few minutes he starts vomiting, so the CIO method has never been an option for us. He's woken up at least twice a night for anywhere from 30m to 3 or 4 hours for over 6 months. We are all completely exhausted and now scared about what the future holds. EoE is apparently pretty rare but that is what my GI is leaning towards. Ive been researching all over the internet for a while and it is only making me worry more

Im wondering if anyone has a child with the same condition or similar or knows anything about it that can help shed some light? TIA
Re: Advice for toddler with food allergies
I have experience with Celiac's, but not EoE (had to google this). We have had my son on a gf diet since that's how we eat and it is hereditary. The one time we did give him gluten, he had a weird rash and didn't poop for 3 days and it was miserable.
Good luck with everything and keep us posted as to what the doc says.
DD2 4.2013 - vbac
DS1 9.2016 - vbac, team green
Baby #4 due 9.2018
My advice is, if it is EoE, definitely see an allergist. My allergist said a lot of GI docs are dismissive about treating EoE with food elimination for some reason. But I really feel 100 times better now than even when I was on my medications.
What my dr suggested when I got diagnosed with EoE is to try an elimination diet of the main 8 allergens (wheat, soy, egg, milk, peanuts, tree nuts, fish, shellfish), and see if symptoms subside. Statistically, it's most likely to be one of those things, and they're all hidden in so many things. Then you add back in one food category at a time, for like a week, and see if symptoms return. If not, it's most likely not the trigger. That's something you can do while you're waiting on testing, at least! Though if he's going to be tested for celiac, don't cut out wheat because he has to be on wheat for the testing to be accurate!
The other thing my allergist mentioned is that some trigger foods are delayed triggers--so you eat something like dairy today, you get no symptoms so you assume dairy is fine, but then a day or two later you have the symptoms and end up trying to connect it to something you ate that day. That's why elimination diets help, because if you're only adding one food back at a time and being very careful to avoid the other potential triggers, if he starts vomiting during that week then you know it's a possible trigger.