Some betas only live about 1 1/2 years. Since they are about 6 months old when you bought him he may be near the end. Being bowl kept doesn't help longevity. I am not sure what betta fix is, I usually use salt as first treatment before going to the stronger stuff. If you can keep the water temp. somewhere at 78-80F that would be best. Maybe his bowl location is either too cold if the AC is running or too hot if near a window or with no AC. Is he eating?

Try feeding him some mashed peas. Bettas can get constipated and this will cause all sorts of problems.

Most of the male bettas you get from the stores are older than a year, that's about how long it takes them to reach the average size you see in shops. Wallace could be as old as 3+ if you bought him as a full grown male.

I buy my boys out of the girl tank since my 'expert' fish store guy is not very bright and can't tell the diff between a female and a young male. I've managed to get some smashing plakats that way for a much cheaper price.

Good luck with Wallace