Hello there, I think you are saying Watery nasal discharge. If so then most commonly its from nasal allergy but along with this you will have sneezing and nasal itch. Other than this it can happen while eating food . Sometimes rarely it can happen whenever you bend. Its not clear from your history. It may / may not be related to gastrtis.
Usually its not serious but a nagging lifestyle problem, better addressed early.
Next Steps
Please consult an ENT specialist online or face to face
Health Tips
1. Avoid exposure to dust and other allergens
2. Wear a face mask
3. steam inhalation once/ twice daily