Hi, I Have Some Sort Of Boil On My Penis

Hi, I have some sort of boil on my penis which I noticed 5 days ago. I tried to squeeze the puss out but I couldn't get any out. The boil hurts when touched and has gotten bigger in the last few days. I am sexually active and I had unprotected sex maybe two-three days prior to noticing the boil. What should I do and should I be worried?