Tough to say without evaluation.
But in any case, I would say a dermatology referral is needed.
There are various type of blistering-type skin lesions that need to be considered. If amenable, a biopsy may be needed for a more definitive diagnosis.
But that should be determined by a dermatology referral.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin Pho, M.D.
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Either way, three years, get to a doctor - poor healing like that is not a good thing. Get to a dermatologist to start.