Tips on how to sleep train a 15 month old?

So to give you some insight on how our nights go and a little about him he is turning 15 months on the 20th and still wakes up AT LEAST once a night but lately it’s been more. He used to sleep through the night for about a month in September I think? Then he all of the sudden quit. Also something I know that greatly affected him is we had to evacuate from hurricane Michael (we live in Panama City) and we’re bouncing from hotel to hotel in Alabama. He didn’t sleep well at all. Then we got back to our house after a week or so and he then got a very nasty cold. (So bad he kept us both up from 10pm to 3am because I couldn’t calm him down and he couldn’t breathe) since then he’s only slept through the night once.

I always put him to bed at 8pm with a fresh diaper and he refuses to go down without a sippy cup of milk. He gets a warm bath right before bedtime every other night and we wait for his hair to air dry before we put him down. He does wear warm clothes most nights unless it’s hot and the only thing giving off some light is the fan (he sleeps in our room and hubby likes the noise and I think my son does to it’s like white noise.) I don’t know what else to do. He can’t be waking up from a bad dream multiple times EVERY night.

Guys I’m a tired mama and need these sleepless night to end. Please help 😫