Brief Answer:
More details needed.

Detailed Answer:
Hello,
Thanks for the query.
More details like duration if the symptoms, associated symptoms like headache or abdominal pain, color of the vomitus, relation with food in take are required to make a diagnosis.
Most probably it will be a food poisoning, or gastritis.
As a first line management you can take over the counter available antacid/antiemetic combination like pantoprazole/domeperidone combination for symptomatic relief.
Drink plenty of clear fluids to prevent dehydration.
Eat light, bland foods and eat slowly and eat smaller, more frequent meals.
If symptoms persist, it is better to consult a physician and get evaluated.
Wishing all the best.
Thanks

---