Any cuts/sores/bumps that come & go should be cultured for herpes. Within in the first 24 - 48 hours of it's appearance to be exact. No one online can tell you what it is. You should see a doctor immediately the next time you see them.
If you are having problems that your foreskin gets so swollen that it completely covers your penis - you definitely need to follow up on this. It could be irritation, infection or even an allergy.
Also lube, lube and more lube when masturbating!! Be kind to your sensitive genital skin :)
grace