What Causes Pimples And Stinging Sensation At The Tip Of Penis?

When I pee in the morning I feel a sting in the tip on my penis, it s usually only in the morning and not excruciating, just uncomfortable. I noticed a few days ago a small bump on my shaft that looked a lot like a pimple, I didn t think much of it but now I have three on my shaft two on my scrotum and one on my inner thigh. Do you know what this could be? And is it curable? I am sexually active and have had unprotected sex in the past