Skin rash and itching on while body area

I am 35 m 82 kg  non smoker non alcoholic not diabetic suffering from.skin problem not getting relief from past 2 months.took lot of medicines even prescribed by my doc.the itching and rashes started from genital area and over the past 20 days it comes upto throat.now no  and rash in genital area.but its on stomach arms shoulder mostly.attaching some pics. Rashes and itching area increases day by day towards uper body. Skin become leathery where rashes are Yesterday itching come upto throat Doctor told me to take again zempred8 which i took earlier on his advice.but not much relief I am on leave from last 3 months and at home.i always keep my skin hydrated .took lot of precautions but not getting relief. my dr. didn't advice any tests Please advice some treatment Food precautions Currently taking zempred 8 Atrax 25 1AL 5 mg.      Please advice any lab test to perform to know the root cause. Verusia lotion adviced by dr. Lab tests to be carried out to actual find out what it is