First get rid of that charcoal; then do a 25% water change with same temp water and make sure to do weekly water changes from now on. Get some Melafix and Pimafix and treat whole tank for a week according to label instructions.

If you have a local herp vet it's a good idea to have Dr. see frog since they got access to strong antibiotics. Let us know how frog reacts to treatment two days after it starts. Good luck !