My prick & blood rast test for all foods was negative but when i eat any food except whole wheat i get very itchy flaky scalp and excessive hair loss.

Itchy scalp: This is not a food allergy, but a skin condition in your scalp that needs to be addressed properly by a dermatologist.

Unusual: It is highly unlikely that you would be allergic or intolerant to all foods other than whole wheat. Recommend that you consult an allergist to consider doing some food challenges to see if you are indeed allergic to intolerant to the foods you implicated. I don't want you to get in a nutritional bind.