4 months old flip in his sleep but face down

Hi mummies, please dont scold or bash me as im a first time mum and still learning. I know we shouldnt swaddle baby once they have started to flip. But my almost 4 months old need to be swaddled for him to sleep else he will cry murder. And yes we’re using white noise etc but the important thing is swaddle. We’re using the velcro swaddle. Sometimes his hands would break loose. Sometimes its fine. Past few days altho he has learnt to flip, he still sleep peacefully without moving much. However this middle of the night to me surprise, I heard a cry thats unusual. So i woke up instantly and he was already flipped on his tummy, and his face was facing down! And he was struggling. Really thank god i woke up on time else theres a chance he might suffocate himself. Altho he knows how to flip, sometimes when he’s tired or sleepy, he woulnt be able to lift his head much and would end up face down. Any mummies experience same thing and any tips to make sure he wont flip when he sleep? And also he’s down with bad cough i think thats what made him woke up in the middle of the night, which usually he would sleep through the night.