Intense itching and burning

I am a 51 yo man, very physically fit running and working out 3-5 times per week for an hour or more.

About early April of this year I experienced a period of intense itching on my upper chest. After two or three days I noticed a rash of small blisters had appeared. The blisters were diffuse in occurrence and totaled probably no more than a couple of dozen. After the rash on my upper chest disappeared, I had a bout of intense itching on the tops of my feet. I scratched so hard that the skin was removed leaving sores which have still to heal completely.

At first I didn't think the two episodes were related. But a short time later I began to experience prickles and itching all over my body. The worst areas seem to be my scalp,groin and lower legs. I have had periods where the palms of my hands and even the tops of my toes itched beyond relief. These areas also experienced burning painful sensations after itching them.

I've noticed that rubbing my skin on my forearms against s