How To Get Rid Of The Body Itching Problem ?

Hi I am having a body itching problem since 8 years.. every 3day I had to take cetzine in order to control the itching... I went to Bangalore Allergy Center 5 months back and they diagnosed this rashes problem is due to dust mites .. They had given me some medicines..It was normal till last month.(April).. But now the problem again becoming worse... Now I again started taking cetzine once a week. Please suggest how to gid rid of this problem and what sort of test I need to undergo in order to find the exact root cause of this itching