Hi,
Welcome to health care magic,
First of all,it would be better if you can tell me what blood work has been to her so far.
The causes of nausea or cold sweats after eating certain foods could be anxiety or stress or
orthostatic tachycardia syndrome which can also be triggered by eating certain foods like refined carbohydrates,white flour.
She must go to physician or cardiologist to check your EKG,2D
Echocardiography of heart to rule out any heart pathology.
There are many causes ,however, I would like to have more of your medical history and information like,
1) have you checked her blood pressure while having an episode?
2) have you experienced her dizziness after eating anything special food?
3) are the episodes common throughout the day or certain moments?
If her blood pressure comes normal,then, it might be because of disturbances in the middle ear like
labyrinthitis or spondiloarthritis.
So, I' would suggest you to consult with
ENT specialist and
neurologist.