Hello, Welcome to healthcare magic. Sometimes, the deep cracks and fissures could be associated with plantar psoriasis. You could consult a dermatologist who will probably look for clues on other parts of the body like scalp, nails, elbows and knees to rule out psoriasis Meanwhile, you could try to heal the cracks by applying ointment containing povidine iodine into the cracks and a cream containing Shea butter, glycolic acid, urea and lactic acid ( emmollients and humectants) around the cracks to soften the feet. Do this twice a day. Use soft soled footwear with thick socks preferably. Hope this helps you. Take care.