What Causes Soreness Under The Head Of Penis Post Intercourse?

My friend and I have been abstinent for over a year. For the last 9week s in a row, we have sex one night every week. Typically on that night, we have sex 3-4 Times in a 12 hour period. He has been complaining of.being raw and having pain beneath the head of his penis. We have tried multiple treatment like A&D ointment, antibiotic ointment, fungal creams, etc... He is still complaining of soreness and being raw. Like I said, we usually have 6days between sex. I am.not having any issues and we are std free. What is your suggestions for treatment options?