I am 60 yrs old and have a sore that doesnt heal completely in childhood vaccination mark. It healed up once but when I had to use prednisone it came back and though Im off prednisone now 3 months it doesnt improve. Its been there 2 yrs. It has a crater and gets a white crusty scab on the outside of the normal scab . Whenever the scab come off the inside isnt healed. It also will leak clear fluid occassionally. Itch and sting on rare occassions. There is also a white halo around the whole thing. I had systemic candida 7 yrs ago and wonder if this could be a fungus in the sore.My immune system isnt the best, many allergies.