Nightmares are common and most people have them from time to time. A single bad dream, even a vivid one, is rarely a cause for concern.
It may be worth talking to someone if nightmares come often, leave you afraid to sleep, affect your days, or began after a frightening event. A dream dictionary cannot assess this, and nothing on this site is medical advice.
Your GP is a good first step. The NHS lists mental health support and the charity Mind has information on sleep problems.
If you are in distress, the Samaritans offer free support at any hour on 116 123, and via samaritans.org. In an emergency, call 999.
Small habits sometimes help with ordinary bad dreams: a regular bedtime, less screen time late at night, and writing the dream down in daylight so it loses some of its grip. A journal is a gentle way to do that.
This guide is general information, not medical advice. If dreams or sleep are affecting your health, speak to a doctor.