I think Sidney and Smokey may be kindred spirits. When I brought Sid back from the vet last Tuesday, he was super, super stressed, and panting. That's when he had the fever. I had to take him back on Thursday (started the antibiotic on Tuesday) and the fever was gone by then. When Sid came back he drank a half bowl of water. I think this may be a stress response, tbh.
Hey, at least Smokey is eating. That's really important, though I wouldn't let him gorge if he was having tummy trouble earlier.
When I was first testing Sid's ketones, I had a day or two where it hovered between negative and trace. I think sometimes it depends on what light you are looking at it in. It looked...blush coloured a few times, but not the same as the trace color.
I made sure to keep adding water to the food to keep flushing any possibility of ketones out. Days where I saw trace, I would test two times. I've heard, though keep in mind I am new and not sure if it's true, that anything above trace is what is to worry about, but seeing trace is about monitoring and trying to flush them with water and such. Again, I have read people who have gotten the same result testing them and their cat, so try to look at it next to a window in the daylight to get a true picture of what's going on.
I'm lucky that Sid lets me use a tiny paper plate to catch some of his urine (I just slide it under, then go check the clock and dip the stick. Don't read beyond the 15 seconds, as it can darken more.
I'm thinking good thoughts for you and Smokey! Get that antibiotic going and then we can go from there. I'm really nervous about starting all of this, but we can do it. Just have to go one step at a time. Though these cats aren't making it easy by getting fevers and needing antibiotics. Crossing fingers all stabilizes for our kitties!