If there is still food in the tank, the up and down swimming is the young frog being excited by the smell. You said you use both floating and sinking foods so it thinks it has to look all over for the meal.

Frogs will also occasionally do this - they can not "see" the glass so the swim until they hit a barrier then they swim up and down the barrier until they are satisfied there is no way through.

Both of your frogs are new and young. Being first shipped to the store, put in a new tank, caught in a net, bagged and then put in another new environment is extremely stressful...Stressed frogs will go off their food for even a few weeks with no ill effects.

Just keep feeding and be patient. The frog IS eating a bit so I am not as concerned.

Do you know you water stats? A healthy environment will help ease the transition.