Haven't worn earrings in awhile but a rash keeps coming & groin behind my ears. what could be causing this?

More info: It would help to know if the rash started while wearing the ear rings. Also, where behind the ear. Briefly, in the fold of the ear and skull rashes can be as simple as dandruff. If that, likely would improve with dandruff shampoo. If on the earlobe where the post comes through and started with ear rings than allergic response to the ear ring possible. Limited info makes difficult to say.