Thanks for writing in.
The most common cause in your case is candidial balanitis
It is caused by yeast called candia.
Oral and topical antifungals are the treatment.
can cause recurrent problems like in your case.
You should get your fasting and postmeal sugar levels done.This will rule out diabetes.
Also to prevent recurrence of balanitis a short surgery called circumcision
may be required.This will cure the problem once and for all.
I encourage you to visit a qualified dermatologist
for proper advise and treatment.
Hope this helps.
STD & leprosy