What Causes Red Patches All Over The Body?

hello doctor my name is umesh satpathy and i am having frequent skin allergy.where in small red spots are visible in the body and gradually it is becoming into big patches throughout the body,having mild itching irritation.I have consulted local skin specialist here and the doctor has termed it as "SEVERE URTICARIA".during october 2009 it was quite severe and local doctors precribed steroied injection which I took for 4 days again it occured in january 2010,then in january 2011 and now I am suffering from it for last 4 days.Medicines taken are L CETRINE 1x3 for 15 days and 1x2 for 15 days,and i was taking 1 tablet daily till this time.now i am taking this medicine 3 times a day.but no remedy for last 4 days.please adivice me the treatment.now i am having red patches in my body.thanks