Orthostatic or positional vertigo is another possibility.
Hypoglycemia and severe anemia and or GERD or gastric reflux could be other
causes. It could also be a vasovagal syncope or a vasovagal attack. The complex group of symptoms is mediated by the vagus nerve. This nerve is irritated by prolonged standing, standing up suddenly, stress, pain, hunger, dehydration, intense emotion etc. A tilt table test, holter monitor, echocardiogram etc are done for confirmed diagnosis.