What to do about rolling back to belly?

Hi! My son is almost 6 months old and about 4 or 5 days ago learned to roll from back to belly in the middle of the night -- it was loads of fun (not!). He has not mastered rolling belly to back yet, so you can imagine how it went. He has since started sleeping on his stomach which is fine with me, however I am not sure how to handle when he wakes up in the middle of the night on his stomach and can't roll over / is upset about being in that position. He is mostly sleep trained, but we got into some bad habits over holidays and sickness, and I would like to go back to not responding to non-feed wakes, but I feel like I have to go in there and help him off his stomach since he cannot do it himself. He just gets REALLY mad when I do that, I cannot calm him down, and I end up nursing him. That does work, and this only happens for about 1-2 non-intended feeds (I allow for two usually), but I really don't know what to do so Im looking for advice! Thank you :)