Red rash skin wth itching. Some thing.

Red rashes on skin with server itching only at evening every day, on figure of hand, feet, palm. aggravate more with scalp, ear, Peri-orbital lines of eyes. more dandruff is observed. get cured immediately with citrizine. i am having this problem since last three month, i believe it started with after having Chavanprash (don't know exactly). Dermatologist prescribed citrizin two times a day for one month. did not saw any difference. then second treatment was Prednisone 5mg for 8 days Twice a day. Still problem is there. Even a small scratch make skin redish. at evening the itching is exactly similar to the mosquito bite, fast and intensive. My Uncle is suffering exactly same problem since last four year. Kindly suggest some thing ... Regards Sangmesh