How To Treat A Large Bump On The Anus?

I took a shower tonight and noticed a rather large bump on my anus it s under the skin and almost covering the hole it popped up very quick it s not painfull but is constantly a discomfort I pooped an wiped fine an hour before I took the shower I m very concerned I m 22 years old I don t the most healthy things but not too bad either it is the same color as the skin maybe a little darker I moved into a new house 3 or 4 weeks ago and it wasn t all that clean when I moved in and I ve been using the couch that was already here I could really use some help and some cures I can do on my own thanks