Alley has a hyperthyroid, looking for advice

Hello all it's been a while since I've been on. Alley our other sweetie just turned 15 a month ago. We found out last Friday that she has a hyperthyroid. Per the vets advice (went to my sister's cause ours couldn't see her) started her on methimazole on Saturday. Gave her the whole pill cause I had no way of cutting it. On Sunday we cut it in half she was good for two hours then was sick to her stomach. Should note here that Saturday we had no issues at all. She was also given a dewormer so we weren't positive to which she was having issues with. She was sick one other time on Sunday sometime between when I went to work and came home for my lunch break. That time it was food that came back up. They did put her on the y/d food which I have been told elsewhere is not supposed to given while doing the pill. We stopped both the food and pills for a couple days just to see if by doing great so it would give her system a break and time to recoup. She didn't hardly eat much on Sunday. By Monday evening she was back to eating like she was being starved and Tuesday she had a good appetite too. We were giving her fancy feast those two days. Yesterday she had what we think is a bladder control problem, she came in very dirty and smelling like pee from being outside. We tried to call our vet but because they didn't run the labs they want us to call my sister's vet. We think she needs to be seen by a vet but I don't know if she could survive a two hour car ride right now. I'm very frustrated that our vet keeps telling us to call the other one. We thought we could just transfer her care back to home so in case of an emergency we don't have to travel so far. I had to work yesterday so we just did nothing hoping our vet will be more cooperative today. She's just not herself and not eating and not drinking. We did give her another small dose it the thyroid medicine last night, this morning there's not much of a change. Does anyone know if this is normal in a hyperthyroid kitty as they work to adjust levels? I'm scared, sad and worried.