re: Any veterinarian’s on here that would chat for a minute

No you can’t “nuke” him with preds, you won’t do any favors to his kidneys, which may already be a factor. So no blood work huh? It’s highly probable the cat hurt/ slipped a disc in his back jumping off something. Won’t show up on X-ray. CT scan is what will show it, but it’ll be fairly expensive. I would do my best to make sure he doesn’t jump up or down on anything for a few day and let him rest. Maybe a benedryl fro a day so he won’t be prone to moving a lot. Without more that’s about all there is to it