It sounds like SBD (Swim Bladder Disorder). Most fish have an internal organ filled with gas to control their buoyancy. They can alter the level of gas contained in it so that they don't sink to the bottom or float to the top.
This can be caused by a number of things. Since he is not eating now, most likely, your betta was overfed, causing the stomach to enlarge and press in on the swim bladder.
Fast your fish for about 3 days. If the swelling doesn't seem to go down, then fast your fish for another 3 days or so (bettas can go up to a month without food). If, after a week or two without food, the swelling hasn't gone down, try feeding it a shelled green pea or some daphnia to act as a laxative, as it's possible your betta is constipated.
If it still doesn't work, it's possible the bladder may have ruptured. In this case, all you can do is resume feeding him (DON'T overfeed) and hope for the best.
__________________
-Proud Nerd 
-Proud Trekkie ll\/ll
-Proud Fencer -----(-
Quote:
|
"If a mime dies in the forest...do they make a sound?"
|
|