I had bipolar II diagnosis as well a few years ago. Got rid of it with detox (methyl B12 and Xymogen's Opticleanse).
Found out I had Lyme disease shortly afterwards. Lyme can mimick any disease. So yeah, keep searching until you find the cure. Methylation support will really help her as well. Also most bipolar people are vitamin/sleep deficient. So you got to find out what is causing it. Parasites, atlas subluxation, spheno-basilar joint dysfunction, and pyroluria/porphyria come to mind.
Best of luck!