Rae, sorry about your frog. This may come too late, but losing control of the back legs could be a sign of metabolic bone disease/lack of calcium. I know you dust and gut load your crickets but there's any number of variables affecting how much of a given nutrient is actually absorbed by an individual frog. I think someone already mentioned the pedialyte/honey bath. You could also mix that solution with some of that calcium supplement you use to dust your crickets. Exoterra has a liquid electrolyte and D3 supplement sold here (first item). I've never used it though, but it seems like it could be helpful for treating calcium problems.

The bloating could be due to impaction. Is there any risk of that in their enclosure? Finally, there's a chance all of this is caused by a disease or infection, and if so, there may be no alternative but to seek help from a vet - though you've already indicated that this is a problem. A last resort might be antibiotics like metronidazole or duramycin, but you need to find a suitable concentration and dosage. I may be able to help with the research, if it comes to that.