What Causes Blisters On The Underside Of Testicles?

Male, 64 years old, about 5ft 10in., weight about 163 and have emphysema and use inhalers but not on oxygen as yet. I have recently developed an unusal condition on the underside of my one testicle. I noticed that I apparently had blisters that broke because after taking my shower I had spots that looked like they had been blisters but all that was there was the skin that was loose. They never itched and I wouldn't have known about them If I hadn't looked at them while trying to make sure I had dried thoroughly under my testicle. Do you have any idea what this may be and what might be causing my problem?