I would conduct fecals to check presence of parasites in toadlets. If they are together and $$ is an issue; probably need to do fecal test in one, since all in the "bulimic" group exhibit same symptoms.

As long as frog size is the same; if it comes positive, then only need to buy more medication to treat all frogs. If fecal is negative; then would try to continue offering much smaller portions every 3 hours or so.