I have a spot on my nipple that is darker in color than the rest of the nipple. It is also raw and sore.?

Nipple changes. Sounds as though you may have paget's disease of the nipple/ breast. Paget's disease is an uncommon type of cancer that forms in or around the nipple. More than 95 % of people with paget's disease of the nipple also have underlying breast cancer; however, paget's disease of the nipple accounts for less than 5 percent of all breast cancers. See pcp or gyn for evaluation & treatment options.
Take it Seriously. Lesions of the nipple in women can sometimes be due to paget's disease of the breast which is a type of breast cancer, accounting for only up to about 3% of cases of breast cancer in the United States. Benign keratosis can occur on the nipple, but never assume such a lesion is benign. Go get it check out by a doctor. You will be glad if it is nothing and if serious the sooner treated the better.