Hello I have skin itching since past one year, I had consulted couple of dermatologists but only when I take medicines there is relief. Again the itching starts once I stop medicines. One places if it itches , then again immediately there is continuous short  itching in two other places of the whole body each time, it's like triggering other areas. I did talk to the dermatologist about, he asked me to take the tablet whenever there is itching and to ignore it. I don't have thyroid or sugar. But I take BP tablets. My ESR is 22. Is there any blood test which will identify the kind of infection I have? Pls advise