Cat-Calls and Conundrums

I had planned on coming home and working on that puritan dress I got from Alaina today, but the moment I walked in the door, I was greeted with a scream from my darling kitty, Sugar-Pup. She was curled up in a corner, convulsing and screaming but then after, would return to her normal happy state (to some extent). Her being 20 years young I quickly rushed her to the vet clinic up the way whilst she screamed and cried but she never bit as cats in extreme pain do. First off, my tiny little kitty weighs 5.67 lbs, and she should weigh 7-8 lbs, but she's always been tiny and light, but as for the seizures...they weren't hardcore, but convulsions.The vet said that she had never before seen anything like this and I had to chose between two options; Do a blood test that runs about $94 or give her some Valium and injected liquids for $75. I chose the latter due to her age...so at least for now, my darling dear is doped up and snoozing peaceful in her little bed. I'm relieved and glad I took her in because the vet told me that she's not in pain but scared because she doesn't know what's happening to her. A mountain on my back was lifted after that because I don't want her to hurt ever. Every so often when I glance over at her, she is shivering but never screams, which is good. I've had her since I was 2 when she followed me home and never left since...she's actually afraid to go past the stone walkway. Once she got shut outside when I was bringing in groceries and she freaked out, but luckily I noticed this right away so I was only for a few seconds. Else she might have sat there all night. But this cry is completely different from the one today, it completely chilled me down to the core. Putting her down will be the last thing I want to do but right now it seems inevitable, I just want to enjoy what time is left. Sugar-Pup is definitely not your normal cat though, she loves people and acts more like a dog than a feline queen. Everyday she's right there to greet you when you walk in the door, purring and rubbing against you...I'll never be able to have another pet ever again lest I be disappointed in their personalities.