I'm sorry to hear that. Three weeks is a long time without food and you should probably force feed. I would recommend starting with the worms because they are easier to digest. How big is your frog? If he is under 2 inches then you probably don't want to give him a mouse.

We could use some more info. Is the frog showing any other physical symptoms? What are the terrarium conditions? Temp? Humidity? Substrate? etc. Also, how big is the tank? When Loki was a baby, we had him in a large critter keeper. One day I checked on him and he was trying to climb up the walls and bumping against them. I moved him into a ten gallon and he has been happy as a clam ever since. If there is something wrong with their conditions they will sometimes try to get away. Say if the substrate is too wet or too dry... check to make sure their isn't anything irritating your frog. You are going to need to get some food into him quickly though. Good luck and keep us posted.