My almost 7 month boy was sleeping pretty well in the night until a couple of weeks back. (Feed around 8plus, sleeps from 9 to sometimes 2-3 ish, at times 5am for feed) He has been waking up crying, 2-3 times each night. His bottom two teeth are out. Any idea what else could it be? He has been sleeping in his room since he was 4 months old and we have a baby monitor.

Hi this may just be a phase as he goes through a sleep regression or a growth spurt. Anytime the baby is going to have a milestone development for eg having teeth out, learning to crawl etc they will have a phase of sleep regression. It will become better again. It hap to my gal for a while and I was puzzled too but she reverted again. Maybe his gums are sore. Try not to start anything new during this period for eg if he usually wakes in the middle of the night to feed then sleep , continue to do so but don't rock him to sleep or play with him etc . Don't start a new habit. Maybe try to soothe him back to sleep by patting him a bit or give pacifier and some milk.