Is melanoma the only explanation for changes such as dark raised patch and roughness in texture in an existing mole?

Moles: Particularly in winter dry skin can develop. This can result in dry rough patches on moles. It is hard to tell without seeing a picture. Please show your doctor the spots in question! Best of luck!

See dermatologist: I would first be certain that this lesion is infact a nevis. A visit to the dermatologist would confirm that. Sometimes there are lesions that might resemble a mole, but might be something totally different, e.g. a seborrheic keratosis. This type of lesion occurs in middle age and might go through the changes that you have described.