If the scars will absolutely not go away would it then be alright to try IPL or laster surgery or dermabrasion?
I'm not sure it really was a yeast infection--eczema is much more common on the penis than yeast--but neither one leaves permanent scars. Mederma is not dangerous, by the way, so you did no harm. Don't laser your penis. Just leave it alone for a few weeks, minimize friction, and apply only vaseline or some other moisturizer. See a doctor after that if the mark are still there--you may need a medicated cream. But I'd be very surprised if the marks don't fade completely. Just give them a chance.
Best.
Dr. Rockoff