Suggest Treatment For Itchy Urticaria On The Body

I had some dental treatment done recently.I have been taking Phexin and Enzoflam.At the end of the 5 day treatment period a generalised urticaria appeared on most of my body with unbearable itchy skin.Lesions differ in size and shape,from small to large with a red purple colour.I went to the hispital,been given an IV injection with antihistamine and some steroids?Also I m taking a pill(Allegra 180),fexofenadine Hydrocloride.
I m worried about the fact that nothing has improved since yesterday,after the hospital,lesions look worst actually today also cannot stop the itchyness.Please please advise,any suggestion is greatly appreciated.Many thanks,