Unfortunately I cant answer anynof the medical questions. Although I would think if she is improving with the melafix treatments, then continue it for as long as possible, ie. Until she improves no further.
She may be off her food due the being moved to a new enclosure and being a little stressed. To my knowledge mealworms have much harder exoskeletons to crickets. A crickets body, especially when small enough for FBT'S actually has a very soft body.
Can you feed the superworms or mealworms to birds? I had a load of crickets in my last tub which were to big so I saved them and fed them to the chickens at work ...