Hello,
It can be due to verruca vulgaris or warts. Warts are tumours or growths of the skin caused by infection with Human Papillomavirus (HPV).They are contagious when in contact with the skin of an infected person. It is also possible to get warts from using towels or other objects used by an infected person.
These can be light or dark. They are usually oval in growth and raised forming rough surface in the skin. Get an evaluation done from a dermatologist to confirm the diagnosis.
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.