It sounds like either dry skin or mild eczema. If Lubriderm didn't make much difference, I suggest you try 1% hydrocortisone (over-the-counter)
twiceTwice-a-day a day for 3-4 days. If that doesn't help, you should see a dermatologist. But it doesn't sound too worrisome. Skin does this sometimes (including penile skin), often for no specific reason, though in the groin friction from exercise or sex could play some role.
Best.
Dr. Rockoff