I am a 45 year old female. I broke out on my arms & back with these sores that will not heal. It's been 3 months & I still have them. They started out looking like a small, red dot. Within days the dots turned into larger, crusty, open sores. They're discolored except for the skin at the very top, which is white. I put Neosporin on them & covered then with bandages, but it doesn't seem to help. The sores are dry and thick callous skin. The sores don't itch, but there's slight pain when pushed on. Why won't they heal?