I wouldn't be too worried about impaction, especially if it's coconut fiber substrate. Pacman frogs will inevitably eat some dirt, but as long as they are eating other things and their environment temps/humidity is correct, they will be okay. Only thing to remember with paper towels is they need to be changed frequently so they don't become a breeding ground for bacteria. Give it a try and see if simply having a place to hide helps ease her stress. If she doesn't improve, however, I would recommend giving her dirt so she can burrow and hopefully feel safe that way.

From here, I would give her more peace and quiet and try to put crickets in there overnight. In the wild, night is when they usually feed, so the privacy and timing might be enough to get her to eat.