Severe itching all over the body, small rashes, taken medicines, temporary relief. What should I do?

Hello Doctors, I am suffering from seviour itching problem all over the body from last 5 months. While itching some times small rashes also appearing with red color. Itching on the scalp, neck, hands, legs, back, thies, foot. I have consulted four doctors till now. but still facing the itching problem. if i use the tablets, tempararily it works and itching not comes on the body. if i not uses the tablets itching starts like pin biting. I have used the tablets ( fexofenadine hydrochloride tablets, montelukasi sidium, levocetirizine hydrochloride, excipients, levocertirizine dihyarochloride, methylcobalamin , alpha lipoic acid , folic acid vitamin b6, benfotiamine). One doctor prescibed the tablet to improve the immunity also. I am unbearble when the body itches. Kindly suggest me to cure my health problem.