This happens to me when I take Zyrtec for seasonal allergies. It usually starts off with itching on
the tip of the penis, especially the skin
. The head of the penis sometimes has reddish spots, and as you noted, the skin drys and peels off on both the head of the penis and the skin covering it. The itching turns to minor pain a week or two later as the skin drys and stretches, almost with very tiny tears. Anyways, as I mentioned, it starts when I take Zyrtec and stops after that.