Pimple in pubic area

I had unprotected oral sex 3 weeks back. About a week back, I developed a large pimple in the pubic area. I have got pimples in this area before and this was no different. However, the pimple grew to the size of a small pea and became very painful. The head developed and it filled with puss. After a few days, it broke and lots of blood and puss came out. By the next day, the pain had vanished and the pimple diminished in size. Presently there is a small hard lump just under the skin with flaky skin on the surface. There is no pain or itch, but this has never happened before.

I also noted a few tiny red spots on the head of the penis, which disappeared in a few days. These were more prominent when wet or after I masturbated.

Could this be anything serious?