16 month old won’t sleep through the night 😵‍💫

for the last 3 months my son is waking up screaming crying in the middle of the night & I mean screaming to the point snot bubbles are coming out of his nose and he’s about to puke cause he’s crying so hard! I don’t know what to do anymore. the only thing that seems to stop him is laying down with him in my bed and patting his bottom till he falls asleep. im 29 weeks pregnant and I need advise fast on how to get him to stop doing this! I don’t think it’s a sleep regression at this point cause it’s been going on so long now. 🥲