As you have got this problem since long, try to find out cause of having itching.
There might be having some external causes like soap, cosmetics, clothes, spray etc.
There might be having some internal causes like, worm infestation, diabetes
and even in thyroid
Take Antihistamine like Cetrizine
, Levo-cetrizine instead of phenargan.
Apply moisturizing body lotion.
Ok and take care.