My dad has got itchy black spots on sun exposed area like hands face neck and legs. He has been taking medications since 2 months now. But there's no sign of healing. The earlier spots are healing but new ones are coming up. The doctor told him it'll take time to heal but it's been 2 months already. Even the mosquito bites are turning into those black spots. Yesterday there were itchy dark rashes on his lower back. I'm really worried. Could it be something else? Like a skin cancer or something?