My African Dwarf Frog Arm Injured?

I noticed recently that my ADF's front arm is injured and he doesn't like to use it very much. He still swims to the top to get air perfectly fine, but he just favors that arm. I have in an isolation tank at the moment and have added aquarium salt and stress coat to it hoping that it will help him. Has something like this ever happened to their ADF? Will it just heal on it's own?