Welcome to HCM
We understand your concerns
I went through your description. I sincerely think there is nothing to worry. You are supposed to be a healthy person. The description is incomplete even though. You should have mentioned your age and any other medical conditions you might have.
You went shopping. Try to remember what happened on that day of shopping from morning. Not what are all food you ate on that day. Where you went, any peculiarly smelling or feeling places? Were you drunk the previous night? Had peanuts or peanut butter before having iced tea? Had any incomptible foods like milk and fish? Etc. There are so mny reasons for feeling light headed and nauseous.
You vomited OK. Vomiting
happens because your stomach is irritated due to some foreign objects of it is not capable of digestion. What happened after vomiting? How many times you vomited? Able to take food after wards? Got a good night's sleep?
If the answers to the above questions are positive, nothing to worry. If negtive consult a general physician.
Hope this answers your doubts. Available for further clarifications.