Swollen foreskin from excessive masturbation?

I have been masturbating more frequently than usual and have been prolonging these sessions for much longer than I normally would, but have begun to experience some discomfort.

When flaccid, my foreskin normally covers the head of my penis with some to spare. Although this is still the case, the area at the top of my foreskin is quite swollen and looks puffy. Further down along the shaft, the foreskin looks and feels normal. It is difficult, but not particularly painful, to retract the foreskin because of the puffiness.

When erect my foreskin always retracts. There is some minor pain and the foreskin looks a little swollen but it doesn't really inhibit my erection, other than feeling quite tight around the swollen area.

I expect I should stop masturbating for a while, but does anyone know if there is something specifically wrong and how long I should refrain from masturbation for? I'm hoping I haven't caused any serious damage.

Thank you for your time.

P.S - It's important to say that I am not sexually active and so run no risk of STDs.