I am a woman, so I don't know if I can be much help, but I would listen to Bob, and drink more water as Lapdogblue has suggested.
Is it possible that you have a yeast infection? It it red and itchy? If this is the case, sit in a bath with about 6-8 drops of tea tree oil for about 20 minutes and repeat.
If it really is only from chaffing, maybe wear a tighter fitting cotton underwear. That way your penis won't move around as much and thus will decrease the chance of your foreskin chaffing.
Perhaps it's a simple case of hydration? Do you drink a fair amount of water or moisturize often? That's what I would suggest before going to a dermatologist.
Hi try a good Antiseptic cream , when better use lube Take care ...Bob