I doubt that very much is wrong. This sounds like little more than residual irritation, which leaves behind redness that can last a long time, means nothing, and goes away best when left alone. As to the erectile dysfunction, that can be from worrying that you got something or can spread it. If your worries persist, you can show another doctor, perhaps a dermatologist or STD specialist your penis. But since you've already been examined by a urologist, I can't imagine what else they'd find....
Take care.
Dr. Rockoff