Fire Bellied Cricket Troubles. Th

[Fire Bellies]

Hello, I am the owner of a fire bellied toad and I am having troubles with my crickets. It's been happening for a while and it's driving me crazy. For some reason I find them either on their backs with their feet dangling in the air, or found dead upside down. The ones I find alive I flip back over but they limp around for a bit awkwardly before falling back down. They are in a cage with plenty of food, and only a dozen at a time until I feed my frog. They normally still have their legs normal.
It's been nothing at first because I guessed it was maybe a broke leg or something, possibly the pet store. But I got them from various places so far and the same end results. I've been getting up to five dead by being on their backs at a time (when I buy a dozen) I looked everywhere on the media. But my luck? Nothing. Can anyone tell me what's happens to them! I feel like I'm wasting dozens of crickets Sorry about the title, idk how to edit it. But I need help badly!!!!!