Rash Around Wrist Bone On Right Arm. VERY Hairy With

Rash around wrist bone on right arm. VERY hairy with purplish skin and just beginning to develop pustules. Skin is VERY rough and tender at times. Area keeps enlarging. Going down onto right hand and further up me arm. About 4inches long and an inch to inch and a half wide. Somewhat oval in shape. Area turns gray on top and purple red underneath when dry.