Red mark under foreskin

Hello. For the past few weeks, I've been noticing a faint red marks on the inside of my foreskin. It does not itch, hurt, sting... I do not get any discomfort during urination, sex, masturbation, or walking around. In summary, there's nothing wrong other than these faint red marks that wont go away.
They seem to show up more after masturbation, but they get a lot fainter the day after. And they are nearly invisible when the foreskin is peeled back when Im flaccid.

The last girl I had sex with had herself tested and told me she got negative results on everything. (we had sex roughly 4 months ago)

(by under/inside foreskin I mean the part that is in contact with the head when flaccid)

[Bhupinder Kaur, MD]

Hello,
It looks like chafing skin or friction rub. Chafing occurs when the skin becomes irritated by the friction caused by rubbing either against other skin or against a foreign material. Wash the areas several times with fresh water. Do not use any cosmetic products at the sites. You can apply some calamine lotion at the rash as it will help in soothing the skin. Also wear cotton undergarments. Application of mild corticosteroid cream and oral antiinflammatories like ibuprofen/acetaminophen are also helpful. If the symptoms are severe then it will be best to consult a dermatologist.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.