What Causes Itchy Rash On The Penile Shaft?

I have a itchy rash on the shaft of my penis. I have had an open wound on the shaft of my penis for two weeks that weeps a clear, sticky fluid. The wound has not been healing on its own. A med clinic prescribed an antibiotic called sulfamethoxazole. What do you think is the diagnosis, is the weeping a bad thing, & how do I get the wound to heal?