Gail and Carlos have given you great advice !

If you are unable to get the new substrate (the Eco Earth ) Gail has suggested right away ; yank the substrate and replace it with dampened paper towel.

Water for a soaking dish and the paper towel substrate should be de-chorinated tap only... with a product safe for frogs.

If the one frog is not eating ...separate him a......get him into a smaller temporary tank.
...set-up it the same way
...there, you will be able to monitor his food intake and poop.

Some information about quarantine:
http://www.frogforum.net/general-dis...uarantine.html

The feeder bowl:
http://www.frogforum.net/general-dis...eder-bowl.html