Freeze dried blood worms and flakes are both major causes of bloat and consequently Swim Bladder disorders/infections. Get the temperature in the tank up to 82f and cease feeding for a week or so more, then try feeding him a skinned pea or some thera A (can be found in New life spectrum pellets).
What brand pellets is he getting. The only foods bettas should get are Quality pellets, frozen and live. His belly isn't that bad so I don't think this will be major.
As for the tests, what are you using, that's very odd that you have 6 glass fish and a betta in a 10gal with 0,0,0 actually, unless its planted to the maximum then its about impossible.
Thanks for the advice SK. The glass fish were removed about a month ago. I'll update my profile.
The water testing is done with API Liquid Master kit and while I was cycling and getting results of .25 ppm Nitrite and such I confirmed my results with 4 LFS around me (I live in L.A. so they are all over). I always got the same results. Interesting experiment for a beginner to watch them testing and gain confidence in the process as my tank cycled. Only PETCO used the strip test which on the two occasions I had them test the results were the same as mine.
I will try the peas. I am glad there is hope for the betta. My family loves the little guy!