I get sores that I do not understand.

I have a small round sore just behind the head of my p****. It will turn white and swell for a few days before clearing up.
I get these when that area is hit, especially with teeth. From the first girl to rake it with her teeth to my wife today.
I have been checked for every disease known to man kind, and have nothing. I went to the Dr years back and he said it looked like a herpes sore. But it only happens when I get tooth rakes from oral s**.
It did happen with an older woman who got dry when we had relations. I would get sore and had this same sore. Its only one place each time. Is the same each time.
One Dr told me it could be a yeast infection like women get. Said men can get them as well. He told me I did not have herpes or i would have break outs not related to oral s**.
If you have any info to help me please share.