I have a recurring small cluster of boils every 6 months at the upper base of my penis shaft. if left unthreated form one blister. no fever nor puss?

Genital herpes: If you get recurring blisters that combine to form a larger blister in the same spot, that is most likely herpes. I wonder if your outbreaks occur at times of stress- such as trying to pay an expensive bill, some stress at work etc? When herpes comes out as a 'relapse' it usually is milder than the first time. Try to reduce stress. See a doc if you want to try antiviral medicine, i.e. acyclovir.