I have had an itch today on the top side of the base of my penis and once before a few weeks ago about a day. That time was the morning after I used a condom and I wondered if the condom had something on it that caused an irritation as I did not take it off very soon after sex. The main worry I had was that about 5 months earlier I'd had an encounter with a woman (not regular partner) but a condom was used. However, I wondered if even with the condom the base of my penis was not protected from oral or vaginal sex, if the condom didn't go all the way down the base.  It was just one time then. I don't see anything on the penis that I recognize as a sore or anything. Maybe a little red. Do I have anything to worry about regarding an STD from 5 months ago?