All of the above lol. I had the same problem but I make sure to wash my face ridiculousy good in ridiculousy hot water lol. And even though I was supposed to drink tons of water I wasnt so it helped when I started to

If you are using Vaseline this is very common, also it could be the head guard.

dirty unsanitized headgear probably along with sweat, dirt and the unclean gear.

Maybe it's the vaseline if you're using it.

I'm a boxer and everytime I spar at my gym I breakout really bad afterwards. I don't know if it has to do with sweating or taking hits to the face. Anyone else have this problem?