Hello,
It can be due to fungal infection or psoriasis. What you need to do is consult a dermatologist and get a KOH examination of the skin scrapings and a biopsy of small skin/nail sample done if the symptoms persist. KOH examination of the area will clarify whether it is due to fungal infection or not.
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 doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
could be related to psoriasis.