Hi friend, welcome to HCM.
it is very difficult to tell from here what's wrong.
if heart is OK they say, there could be many differentials. or the heart could be intermittently making her symptomatic.
heart rhythm abnormalities, thyroid
problems, electrolyte disturbances and all such can cause these.
I think you should get her evaluated by a good physician. labs done, including thyroid check (TSH
), ECG, it could be plain anemia
CT/ PET are not helpful before you do basic tests...they hardly help here...
p. keep me posted on the progress.