Thanks for query.
It seems that you might be having infected Sebaceous Cyst
on the part.
It is to be excised and whole sac is to be removed.
If you do not go for removal then it will burst open,cheese like material will come out and it will subside.
But after sometime it will re fill and and same problem will be again.
Unless you get it excised problem is not going to solved.
Ok and bye.