For last two years or so, every time if I have sex or masturbate, the shaft the back side of it connecting to the bottom will turn complete red like a rash. Then after 5 or so minutes the redness is gone and back to complete normal skin color. What kind of infection is this ? I know its not herpes, because herpes don't come and go.

The redness happens only if I have sex or masturbate, or else it just stays normal skin color.



Second question is : I have two small blackhead type of circle black color on the back of shaft. I think before it was a small red pimple, that when poped turned into a white pus and then it went away and turned into a blackhead type of deal.


Are these STD?

Thanks

C