Yes, Our 42 Year Old Son Has Been Having This

Yes, our 42 year old son has been having this happen to him every once in a while over several years and says that now it is worse than ever. He has bumps that appear which so far has been confined to his head area which are filled with puss and blood and when he squeezes it out he says it is a ugly gross mess. What could it possibly be. He also thinks that if the puss and blood get on his skin it causes another one of these.