It can be due to friction of the sole with the ground or due to tinea pedis. Wear shoes that fit properly and keep feet as dry as possible. Also change socks regularly.
And use foot powder to help keep your feet dry.
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.