A. It's common for a cat with upper respiratory infection to stop eating as they can't smell the food properly. The amoxycilline antibiotic can also cause nausea, making it even worse.
Try offering him sardines or tuna, or anything which he finds tasty and has strong smell, try to rub it on his nose if he doesn't look interested. Give it at room temperature or even lukewarm to increase the smell and palatability.
Your account has been reactivated.