There is always a chance that there aren't any parasites involved, but it'as best to visit the vet for a fecal test just in case. That way it can be completely ruled out.
If parasites are found, then your vet can tell you what needs, or should be done from there.
In the mean time, start offering just crickets. Once the frog gets hungry enough he'll eat them. He won't starve himself so no worries. I'm sure he hasn't accepted anything else since the frog meal because he's still full. Give him a couple days and just try again. Don't leave the uneaten crickets in the tank with him though. They tend to either pester the frog and cause stress, or die and cause a breeding ground for bacteria.
Until you can get him into a vet I would suggest setting him up in a very simple tank... a moist paper towel substrate and a bare tank other than perhaps some crinkled up or ripped up damp paper towel for him to hide under. This way you can watch him better and be able to check for "poo". It also doesn't give the crickets any place to hide so you can see when he does eat again and keep track of how much he's eating.
Once you get him to the vet and tested and everything is good, then you can set him back up in his regular enviroment.
Just avoid feeding him frogs in the future, give him a good calcium and vitamin suppliment on about every 3rd or 4th feeding, provide him with a clean enviroment and fresh water and you should have a happy healthy froggie for a long time!!
Good luck!! And I hope that everything works out for you and your little buddy!
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Heather
