Suggest Treatment For Body Rashes, Stomach Pain And Diarrhea

My sister has a rash all over her body accompanied by stomach pain and diarrhea. She has woken up this morning with dizziness, difficulty breathing and itchy hivey rash all over. Swollen hands and feet. She has been to the hospital and has been prescribed Prednisone and Gabbroral, however she is breastfeeding. She is currently taking piriton, can you advise please?