Male Diagnosed After Age 70

My family doctor didn't recognize, and neither did his lab. But after my complaints he sent me to a dermatologist, who thought Grover's, and confirmed with his lab. He recommended triamcinolone acetonide, which is amazingly effective. Minutes after applying, the itch is gone, and soon after so is the rash. Has effected my torso, back and stomach at different times. A bit concerned that the rash was periodic, but lately I've been waking up during the night with the itch. Hopefully, the cream ($2 with my insurance, guessing amount equal to 3/4 cup) will continue to be my miracle.