Sleep issues 2 year old

My son has always been a great sleeper. I could tell him “let’s go to bed!” And he would run and jump into his bed. 3 nights ago suddenly that all changed out of the blue. He woke up SCREAMING “mama mama mama” over and over until he started banging on his bedroom door. Safe to say I got woke up at 2 AM last night and slept in his floor with him because he refused to be alone. Please. Any advice. I’m dying here. I’m 30 weeks pregnant and I can’t be doing this every night.