skin problems

Madison- Grace

Barked: Fri Jun 5, '09 11:42am PST 
Hi, I;m new to the group, just joined today. My boy Malcolm has a severe skin problem. My vet has sent off skin samples and blood samples but still has no ideal what is happening. I have to keep a shirt on Malcolm or he chews and scratches the blood out of his skin. Several places will not grow hair back. He is 9 years old and never had skin problems till a year ago. I don't know if the promaris flea treatment has caused this problem. I don't know what else to do for him. Does anyone here have any ideals