baby choking in sleep

My son is 7 months and we co sleep. People keep telling me to sleep train and have him sleep in the crib because is better for him and me. But my son wakes up choking a lot and im scared i wont hear it if im not right next to him. His doctor said hes okay bc hes gaining weight. And to tilt his head when i put him down. I do that but he will move it back to face up. idk how to make him stop spitting up at night or if i should sleep train.