Rashes lime the one you describe are usually forms of eczema. That means they come for no special reason, and don't correlate with soaps, detergents, and the other things people blame eczema on. Perhpas you know of someone in the family with eczema or sensitive skin. Cold winter weather often triggers eczema. though basically the condition is year-round.
In any case, hydrocrotisone is worth a try. If the nonprescription form doesn't work, you may want to show this to a dermatologist for definitive diagnosis and treatment.
Best.
Dr. Rockoff