Eating problem

[multigravida]

Sorry if this has been posted somewhere, I am new and didn't see a true answer in old posts for my specific question. I have a frog (I have no idea what it is we found it outside a year ago along with 3 others that are thriving fine) that can't eat. He sees his food fine and snaps out at it but misses everytime. It seems there is something wrong with his tongue. I've tried feeding him in a small container instead of his big aquarium but it doesn't help. I can literally put 10 dozen crickets in the cage and he won't catch one. He ate fine before but now he is getting thin. All we ever feed them is crickets/moths no big mealworms or anything that might have bitten his tongue. I am ready to "force" feed him by hand but I don't know how. This is my daughter's pet and she is upset so any help on how to get nurishment into this little guy would be appreciated.