Originally Posted by Kitty Katty
...i notice that he always goggle his mouth...
Can you explain more?
Any time a cat has a noticeable reduction in appetite, there is a serious problem. The bad smell from the mouth can be from various causes but often from gingivitis (inflammation of the gums). In young cats, I worry about diseases like calici virus causing the gingivitis. In older cats, not only dental disease but also kidney and liver disease can cause this. General infections can also lead to bad breath (halitosis).
A few questions.
How old is your cat?
Current on vaccinations?
Can you look inside the mouth? Are there any spots on the tongue? Are the teeth clean and white or green and yucky?
Is he drinking water? If so, a lot? normal amount? less than normal?
Any other clinical signs.
In the meantime, it is very important that he is eating something, even if you need to force feed him a little. If there is mouth sensitivity, then warmed wet food can be both more appetizing and easier to eat.
Good luck and hope to talk to you soon.