Hi, Welcome to Health care magic forum.
As you describe, she is on vegan diet since one year, but 25%of the population may be only vegans, but it should contain proteins, vitamins, fats from oils, etc and it should be a balanced diet.
The reason for the weakness,
nausea, and frequent bruising, may be the
anemia, gastric irritation,
allergy to some thing, or some chronic disease like
tuberculosis.
I advise you to consult a physician for diagnosis and treatment.
I usually prescribe to my patient with such symptoms
omeprazole,
domperidone, multivitamins,
protein supplements, and hematinics till the diagnosis is established.
Let her take more of green leafy vegetables, pulses, sprouts, and protein rich foods, to have a early recovery, and to have good resistance.
Wishing for a quick and complete recovery. Thank you.