Do you treat the spring water in case chlorine is added while processed? Cannot assume that spring water is dechlorinated.

He needs calcium and vitamin powder ON the crickets. He must be supplemented. Crickets should also be gutloaded with healthy foods so that they are at prime nutrition for feeding your toad.

I would reduce how often he's handled, that will be stressing him out.

What are the temperatures?

EDIT - And for the record...petco regularly tells me that I do not need to use vitamin powder with their crickets because of their food, it's a load of bologna. I've stopped arguing with them and just roll my eyes now. Did argue with one woman once because she told me that they were "injected" with nutrients...I said, "you mean they are gutloaded." She said, "No, they inject them." Sure lady, someone sits around with a needle and injects thousands upon thousands of crickets as people buy them...SMH