What happened to my baby??

I changed my son’s diaper right before we went down for a nap, and I woke up to him SCREAMING. I hurried up and grabbed him out of bed, checked him over for something, made sure there was nothing in his mouth, the usual, so I hurried up to change his diaper as a last ditch effort. I take it off and he pooped- okay, maybe his bootyhole hurts. I hurry up and start cleaning his, and he starts screaming bloody murder again- I don’t know what’s wrong, so I’m cleaning as gently/throughly/fast as I can. I then realize after I clean him up that it looks like a piece of skin was ripped off the head of his penis?? I don’t even understand, and I don’t know how to cushion it for him- I have him in the tub right now, but can you guys help me figure out how to help him.