Well, she's had a couple of fits today, though not as bad as what I've seen previously. I did some research on the medication and thyroids in general, and from what I've read up on, around 70% of dogs who have thyroid problems also experience seizures too. So, it does point to her having actual seizures instead of something else. What we're going to do now is put her back on the thyro-tabs and in 3-4 weeks take her back to the vet so they can test her T3/T4 levels and adjust the dose accordingly as needed (as Catlady said). This is what was planned on when she first started the thyroid meds almost 2 week ago, so we're pretty much back on schedule with that.

We're also going to put her on potassium bromide, though it'll affect her legs, it won't affect her liver or her thyroid, compared to the other medication. They're going to first put her on a "loading dose" to get her to a certain level, and once that happens she's put on a "maintenance dose." If she somehow can't tolerate the higher doses at first, they're going to just go ahead and put her on the maintenance dose instead. From there, we take her back 2 months after she starts this medication to see if any progress has been made. That's the overall plan for now.. may change should complications arise before or after all of this. I'm most concerned with her quality of life -- but for now, she seems to be perking up a little bit and that's all that matters. I'll be sure to keep everyone posted. Thanks again everyone.