Is my cat sick or does he have allergies?

if in a week he keeps up the sniffing and sneezing, if the fluid turns colors, if his third eyelids turn red, and if his appetite lessens, call the vet to see in you need to take him in to treat him for an upper respiratory infection. If not, it's probably just allergies. allergies in cats are more common than one might think and can easily be managed. URI's are super easy to treat. they'll give you a broad spectrum antibiotic like amoxicillin, clavamox, or orbax. that should dry him up in two or three days. (they'll tell you all about dosage when/if you get it.) if his eyes turn red it could be conjunctivitis and is really contagious to other cats and often occurs simultaneously with a respiratory infection. Also super easy to treat. there's this stuff called "terramycin" which i don't even think you need a prescription for and you might be able to get some over the counter at your vets office. (proper application is tricky but it works great.) Like people, when cats get all stuffed up, they cant taste their food and lose interest. if that happens, it increases the likelihood of it being a URI. Heat up his food in the microwave for about 10 seconds so it will increase palatabilty (boy, does it stink when you nuke cat food!) But it looks like you're on the look out for all the right symptoms and as long as you're diligent, he should be fine.