my back itches me when i feel warm small and when there is pressure on me.it itches up to my neck and sometimes my arm and lower limbs.it was less when i was in ghana my country .it use to only itch when i do not bath and my skin is exposed to the sun .but now am in china and even sometimes in the cold with little pressure it begins to itch and even if i bath and am in the sun it itches.please help me.