Hello Dear and welcome
There is a little bit correction in your diagnosis it is pilonidal sinus
as pus is coming out of it. In my opinion it is pilonidal sinus and don't be shy to go to your doctor and get it treated as soon as possible. It can a small abscess
and needs only a course if antibiotic.
Pilonidal sinus requires a small surgery and there after it is cured but you have to take some precautions. A doctor see a number of such patient every day so there is no matter to get shy from your doctor. Be comfortable and get examined by your doctor and accordingly treatment can be planned.