I'm going to post the link to the old thread so it's easier to reference: http://www.bettafish.com/showthread.php?t=51226
From what I can see in the picture, the fish looks a bit bloated. Has this bloating decreased at all, or have you seen him poop? Can you recall what the poop looked like?
The distension in the abdomen and the loss of appetite can point to internal parasites--if the poop is abnormal, it would give us a more firm diagnosis. If it is internal parasites, though, they are quite treatable and in my experience bettas and other fish respond very well to treatment and tend to recover in about a week after medicating.