Hello,
Without examination it is very difficult to confirm a diagnosis,but some of the possibilities for your symptoms are
gastroenteritis and dehydration. Drink plenty of water as
dehydration can lead to electrolyte imbalance which in turn can lead to low BP and hence dizziness.
Hypoglycemia, anemia,infections,endocrine disorders like thyroid, adrenal glands, and pituitary gland disorders can also lead to dizziness and nausea.What about your last menstrual periods.