Sandy,
Oh My God....I'm so glad that your vet was knowledgeable enough to get that urate plug out of her, or she may have ruptured something and become septic!
I wonder if its possible that her not being able to pass her waste could have caused the seizure? Its hard to imagine that simple fear of being in the big tub could provoke a seizure, especially considering that she's usually such a fearless, stubborn little thing!
Since she seems to be so stingy with her bowel movements, have you considered giving her a 20-30 minute soak in really warm water every day? I know that, since Charlie has a lot of scar tissue in his intestines from when he was so sick as a baby with an terrible infestation of hookworms, which caused him to bleed internally, soaking him in very warm water every day is the only way that I can get him to go. He has never, in his entire life, been able to pass a bowel movement on his own, without being in water. That may help little Csmpbell Jane to go every day as well,if you give it a try.
As far as her fear of the big tub is concerned, I would invest in one of those plastic "Kritter Keepers" with the neon colored lids like they sell in pet stores, in the largest size. I have one for all three of mine, and those things are great...you can put enough water in them to cover their tummies, and they also have a lid, so if you have to leave the room for a minute, you can put it on, and you don't have to worry about other pets getting to them, or about their jumping out.
Just a couple of suggestions that may help.... I hope she has no more episodes, and continues to improve for you. You've done wonders with her so far. If you keep up the good work, I'm sure that eventually she'll become the healthy, happy little girl that she should be!