Now that you mentioned it, your frog is a male (I am not sure how I missed those "nuptial pads" on his fingers )

I love the name Einstein. My pair of frogs are named Claude and Claudette. How original

Getting back to Einstein. I have never seen gas-bubble disease that severe without seing skin ulcerations. Air bloat usually affects the limbs, but not the entire body. This disease is caused by the frog being subject to oxygen-saturated water. One way to prevent this is not to run your filters constantly.

Gas-bloat and hydrops are not generally fatal, however they weaken the immune system. Watch for skin discoloration, loss of appitite, and swimming problems (float on surface), Bacterial infections are common with these symptoms.

As always, you should consult a vet. Also, I think a "salt bath" will help relieve the pressure. Good luck and you are an outstanding frog keeper for taking in Einstein!

BTW, keep Einstein isolated from the rest of the frogs during treatment.