The Top Of My Ass Crack (tailbone Area) Was Hurting

The top of my ass crack (tailbone area) was hurting so bad for the best few days, couldn't even run. When I went to lay down I smelt something like puss and poop, I look at my underwear and the top on my boxers are wet. Now I'm just using Kleenex to clean it sorta but idk what it is or what to do. Its 3am right now.