What Causes Hives On The Skin?

Hi. Got really bad hives on my skin!Vitamins reaction. Doctor prescribed prednison 20mg daily and benadryl every 4 hours. Took it yesterday and my face now swallowed and all red! I'm worry about Toxic epidermal necrolysis because of the same symptom! Should I go to the emergency ? or my ukrainian doctor on skype told me about fasting , drinking a lot of water, and be calm. What about liver? should i take any medicine to clean my liver?