Hi S.
I have a 9.5 month old daughter that is also seeing the ENT at the end of the month. Her issues have not affected her sleep. She sleeps 11.5-12 hours EVERY NIGHT. Not sure what your routine has been at night or if you have previously picked your boy up in the middle of the night so I want to take a step back. We did sleep train her using Ferber at 4 months...have never had a problem since. However here is my nightly routine
Here is what I do
After dinner, its up to the bath
after bath we have a sing along CD that goes for about 20 mins and she crawls around everythign in her room. we dress her during the songs
Give your baby Motrin. Obviously we do not do this every night but when she has had a cold or is teething, I would give her a shot of Motrin to comfort the pain of teething or cold symptoms
Humidifier in the room. Crank that thing on high to help with keeping the nose clear
prop up the crib (although i think you already do this)
Give a bottle before bed
Put to sleep awake
Does your baby have a lovie??? My baby girl has a special little blanket that is 12'x12; that she loves to sleep with. She has woken up in the middle of the night but finds her pacifier and her blanket and we never have to go in
Which Ever path you choose, PLEASE do not give up after 1 or 2 nights. You need to give your baby time to learn whatever you are teaching him. Plus a nightly routine works WONDERS. Try to keep that same schedule for your baby and other kids EVERY NIGHT...Its gotta be hard with 2 other ones. If you need more support or have more questions, please let me know. I REALLY REALLY feel bad for you. I remember those aweful nights..I couldnt do it for 9 months..mine only lasted 4 and that was too much.
Also I like the other suggestion about the vicks vapor rub on the chest or feet.
Good luck and please give me a buzz if you want to chat more