dermatitis effects the lower limbs mostly. It is mostly from vascular problems in the lower limbs. I would suggest you to get it evaluated from a dermatologist and get the diagnosis confirmed.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.