My foot is a kind of purple on my heel but it only hurts when touched any ideas what is wrong?

Consider these. Maybe a bruise with underlying bone spur. Arteriosclerosis of vessels leading to legs can shower portions of a plaque to any part of the foot, and this is often seen in several areas as purple spots which do not blanch when pressed. Best have it examined by your doctor.
Check Varicose Veins. Since you say that there is apparently no pain upon weight bearing it must be on the side of your heel. This could represent swelling, tenderness from venous insufficiency or varicose veins. This could ultimately lead to a venous stasis ulceration. Compression or support stockings can be helpful for this condition.