I agree! It may also have been the frequent water changes that stressed her a bit
Warm water is good, but frequent water changes in a tank with a weak fish are not
So for next time, it may be good to get a small heater of some kind. I bought an emergency heater for 15€ and it works just fine in the orb if I'll have any sick fish there
It's like a flat plate that you attach with suction cups and plug like usual
A hospital tank needs to be left alone as much as possible, aside from testing the water, observing the fish, giving food and adding treatments.