My cat is having adverse effects to Methimazole. she has a rash, and vomiting. can the rash come back?

Question

This all started on fri. when my cat begain to vomit every 20 min. So, I brought her to her vet and she did a cbc and thyroid check. that is when we noticed the rash. So since all organs were functioning well she sent me home with some antinausea SQ injections. I was giving those but she was not better by morning.I put her in the ICU. They started IV fluids and a steady flow of antinausea meds. The rash was almost gone yesterday and when i saw her today the rash was back and her ears were swollen. so is this normal or could it be something else?