Hello and welcome
Looking at your description, I would advise you to be careful while Standing up from sitting or lying down position.
Sudden change in posture can lead to
postural hypotension, you feel dizziness and may fall down.
Iron causes
stomach upset when taken empty stomach or before food.
Since you are also nausea and diarrhea which might be related to acute
gastroenteritis or food poisoning, I would advise you to go for stool test for ova,cyst or protozoa. you may require a course of antibiotics according to reports.
Meanwhile have lots of fluids including ORS and fruit juices to maintain good hydration and avoid electrolyte imbalances.
you can take antiemetic or antiacidity drug for symptomatic relief.
If you continue to feel dizzy then I would advise you checking of blood pressure and other
blood test like
hemoglobin, CBC and blood sugar.
Hope thsi answer your question, pleas write back to me with relevant medical history and reports so that I will be able to tell you more precisely.
wishing you good health