Pimple like something near anus. Also.

I found today that i have pimple behind my anus since 3 days and it was paining highly on first day but came down much till today when i discovered it as a pimple and i applied soframycin ointment, it is slightly better now but it pains since beginning when touched or if any garment is touched to it. No history of falling, haemorrhoids acc to me must not be there as the pimple is not on anal opening and pilonidal cyst develops on top of buttocks meeting point and i don't have such thing. It is not paining while sitting or anything until it is pressed. I would like to mention that i almost everytime find a bunch of hair at the buttock side and so i want to know that can that hair pluck cause that pimple or is it anything else, since i also had a pimple on my left buttock near the same region before this one which got healed with a topical steroid within 2 days. I had constipation and blood in stool on 29th jan but it got resolved and nowadays am not straining also.