DD is 17 months. SHe is a terrible sleeper - she gave up her morning nap at 9 months old, and only started sleeping through the night on a regular basis at 14 months.
She is teething.
This week she is crying all night long. Yesterday she didn't nap but just cried the entire time. Thought she would be overtired so I put her to bed early, and she played until almost 9 pm and then woke up at 11:30 screaming/crying. I checked on her and she continued crying until after 2 am. I went in at midnight and picked her up, and she fell asleep INSTANTLY on me. I rocked her for a bit and laid her down, and she immediately woke up screaming.
DH refuses to help me at night and says to let her cry. I feel like if she's been cryng for more than 5-10 minutes I should at least go check on her, and if it continues for HOURS then I should be picking her up and comforting her. He sleeps through it, but if she's crying I lay awake and feel stressed.
Any tips or help to get through the crying all night when teething?
Re: Crying at night from teething
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If you think it's the teething - I would give her Tylenol before she goes to sleep.
At the roughest part of teething (when he has teeth about to come out), DS is miserable and I always give him a dose of Tylenol to help him sleep.
And if it's really bad, keep some teething gel around his crib. Because Tylenol does wear off in 4-6 hours and occasionally DS will get up in pain again. But usually he is too upset and crying too much to take another dose of meds so I use teething gel to soothe the pain. Not a big fan of the gels but it's better than him suffering through the pain.
HTHs!
I give DS Infant Advil since the swelling is probably causing the majority of his pain. I hear it works better/faster too. My LO will go through periods when his teeth are cutting where he will do similar things. I never had to rock him to sleep, but when he's cutting his teeth he wants that. I'm sorry your DH won't help you at night. I understand how stressful it can be when your LO is crying all night. Sometimes, my DH will lay down with my DS until he falls asleep and then will put him in his crib after. Would your LO wake up to that? I would try the Advil and then just lots and lots of cuddling
GL 
I feel like I could have written this word for word about my 12 month old. He is cutting his two top front teeth & possibly another one as well. I am right there with you 100%. I've given him Tylenol & teething gel. Sometimes that still doesn't stop the screaming. The second I hold him, he's out like a light snoring on my shoulder. I have let him CIO a few times but if lasts more than 15-20 min I try to get some sleep while holding him on the couch.
GL & know you are not alone!
I was exactly where you are at 14 mo. DD started STTN at 18 mo even though we did loads of sleep training before this and tried everything you can imagine. Try motrin at night, and when your LO wakes, give another dose if you can.
I wouldn't recommend sleep training during teething, but once the teeth pop, we did Sleep Lady Shuffle and it worked really well for us. DD, like your LO, could go on for hours and was so worked up she couldn't calm down to go to sleep. SLS was a great method for her. Don't be afraid too to modify/combine any method, adjust to how your child is responding. Those methods are definitely not one-size-fits-all even though they make it sound like it.
Also, if your DD isn't ready to sleep, it just won't happen unfortunately. I learned that the hard way. At 18 mo. she just decided to try sleeping and with minimal sleep training started STTN. 2 months later I still wait for her to wake up at night and go back to where we were with her waking every 2 hours or more. GL!