When looking into diet change possibilities, don't consider anything freeze-dried.  It may cause more problems than it solves.

An unvarying diet such as hers has been known to cause problems like bloat and digestive issues.  You can't be sure there's an infection (which would be why you would try Maracyn 2) until you've eliminated the possibility that she's just eaten the same thing for too long.  Fortunately, it's not hard to find frozen bloodworms and shrimp at fish stores -- they usually have a freezer right next to the tanks.  Hikari is a well-respected brand.

Good luck and let us know how it goes!