What Causes Persistent Blisters In Armpits And Groin?

Hi, since spinal surgery in 2008 I have suffered with boils and abscesses. They are getting worse and worse. In my armpits and now going up my arm. They were in my groin, but eventually the skin there turned black. Now they are on my inner thighs. The skin is red and hot, eventually calming and then turning black. My GP has given up. What do you think?