What can be the reason for the appearance of bumps and itching on my penis after a massage session?

Hi doctor,

I used to be sexually active seven years back. Then I started going for a massage and used to get a handjob or body-to-body rubbing (not with genitals). When I was a child or teenager, someone gave me a handjob, and a few days later, I saw a bump on my scrotum, which disappeared later. For the past six years, I have gone to massage a lot. A few times, I have seen a single bump appearing on my scrotum and lower abdomen region below the start of the penis, and it is painful and itchy and disappeared in a few months or days. The doctor said it could be folliculitis. Now I have a few doubts; a) Will touching the anus with the other person's finger cause STDs(Sexually Transmitted Diseases)? b) Will the massage where the other person sat on my hips wearing panties while I was naked cause STDs? c) Will licking buttocks by another person cause STDs? After my last massage session, I observed a bump-like thing on my penis, which sometimes is painful and itchy. I have attached a picture. I have itching on my buttocks and sometimes on the anus. I had done herpes, syphilis, and HIV tests three years back, and all were negative. Am I suffering from an STD? Kindly help.

Hi doctor,

Thanks for the reply.

At times I feel itchy and painful there, but when I touch it does not pain.