At the moment I can only think that she is stressed from an environmental change.
Floating plants, subdued lighting, and a dark substrate are ideal for these little fellas.
It can take a while before they start to relax in their new home.
Insure that she is not bullied when you turn your back on the tank.
Try to use a piece of cardboard to block part of the light to create a shaded place in the tanks and watch how she reacts to that.
Try to stuff her like a turkey for a while. It will help to find out if it is indeed an intestinal infection.
Make sure she get loads of brine shrimps, they contain an enzyme that help with the uptake of other nutrients and are very high in protein and fat. Spirulina flakes will also help a lot with guts health, cutted with Daphnia and vegetable foods that will prevent constipation as you will try to overfeed her a little.
Check your fish food ingredients and reject anything that contains any kind of "meal" go for real meat and real seafood.