Thank you (and Lisa!) so much for your advice. We went ahead and sought a second opinion and consulted with a tech who works for a holistic vet. We think it could be a grain allergy from his food (the urinary diet is Royal Canin— not great) because before he switched to the urinary diet he had none of these issues on grain-free, chicken-free kibble. The pain we observed was basically just difficulty standing on his back legs after he laid down for a long time, which sort of just seems like a byproduct of the lethargy. In his bloodwork he tended to test high for sodium after he started the urinary diet. We also just wanted to get him eating again, since he has been eating about half of what he should be. All of this is to say that we’re switching him onto a balanced, high-moisture raw food, so that he’ll keep flushing out the crystals in his urine. Since it’s a gradual change in food, it’s hard to say if things are fixed, but he’s eating normally again and the changes in his energy are showing dramatically! He’s back to 100 mph. I will keep you all updated on his progress. Thanks again for the support and advice! My friend has a cat with kidney disease and told me that a forum would give me peace of mind and sound advice... I owe her a “thank you” as well.