spots under skin burst, thick layers of skin peel...

hi
I am suffering from one kind of skin problem for more than 3 yrs now. The skin of my thumb tip keeps scaling always. Intially i find the hard round spots underbenath the skin of my thumb. then after few days these all spots burst out with thick layers of skin and they keep scaling for few days.Then it resolves again and all new pink skin comes. It remains for few days and then again the hard spots appear as mentioned earlier and burst out again. this kind of cycle runs all time. Within these 3 yrs, the damaged area is increased. Now more than half of my thumb is damaged. I have taken treatments of number of dermatologists and they diagnosed and treated as eczema, contact dermatitis, fungal infection but i never found improvement in my condition. Please help me out if anybody has any idea abt such condition.
Thanks