21,male. 1 mushroom like polyp(not sure) less than 1cm very close to anus.i twisted it. it fell off with little bleeding,no pain!any problem'll occur?

Polyp needs check: If u never had polyps in rectal area, chances are it is not a chronic problem (ulcerative colitis etc), but any growth in this area needs an assessment urgently to avoid progression to serious condition. More commonly skin infection in that area with staph bacteria can lead to abscesses, which if scratched can bleed or ooze pus. They need to be looked at for prompt treatment to avoid complications

Probable skin tak: It sounds most like a pedunculated (with a stalk) skin tag. These are almost always benign, however you should have a doctor look at it to be sure.