Developed a single blister on my shaft and another on my penis head (slight discoloration) roughly 4-5 weeks ago. Dr. prescribed Valtrex 10-day with no effect. Next prescribed 7-day Valcyclovir with no effect. Dr. then said it wasn't a herpes outbreak and prescribed betamethasone 0.05% cream. I've applied the cream for roughly 2-weeks now and the blister on my penis head has all but gone. The one on my shaft has remained and might have slightly worsened. What could it be?