I have a black spot on the heel of my foot. the skin is slightly raised and it is only painful if pressure is applied to it (i.e walking). what is it?

Rule out melanoma: It might be a blood blister caused by trauma or a splinter or sharp object puncturing your foot. Or it may be something more serious. You need to see a dermatologist or other doctor to make sure it's not a melanoma.

Blister: It sounds like you have a blood blister.

Black spot: The black spot is concerning me. It is possible to have melanoma and that needs to be checked. It is also possible it's a hematoma. Stay off it due to pain and get check. Fracture in area coils cause the dark spot too.