You need to get those frogs separated asap. You also need a bigger vivarium for both of them. 5 gallons is way too small. At a MINIMUM you would need a 10 gallon tank for each of these frogs. Preferably a vertical for the gray tree frog. If you don't get them separated and in bigger enclosures, they will both continue to have issues, and the gray tree frog will likely eat the spring peeper as their size difference is pretty big.