Suggest Treatment For Sores On The Arms, Upper Back And Scalp

I have been getting sores on my arms and upper back and sometimes my scalp. They do not go away for long periods they scab over but are easily opened by washing over them with a cloth. They bleed for a bit then get like a clear sticky fluid. they go deep and have even removed pigment from birthmark areas. when they do go away they leave scars and only return in another area. I am at a loss as to what it could be.