Two Things Going On Seemed To Appear About The Same

Two things going on seemed to appear about the same time. Few days before I had a long sex session with girlfriend. Unprotected but been with for a long time. Fast forward about 3 days Worked 2 long a days which I was doing a lot of work and sweated a lot. The next day she noticed what looked like a pimple on the head of my penis. Very small and red a bit raised. Not pain at all I would not have even noticed had she not. I did seem a bit more sensitive after sex that day in the area of the penis slit. Fast forward a week and half. Small red bump has not changed..had sex and was very sensitive for the better half of the day again in the area were urine and sperms comes out of. There might be a small bump on the slit area but hard to tell. No pain when I urinate and read other post after rough sex it's possible to get a infection.