Conclusion
It is normal to have bad moods, but you should not dwell on them. if you observe frequent changes in your mood, it could mean something serious. You can talk to a therapist, to help you.
References:
[1] https://www.medicalnewstoday.com/articles/265214
[2] https://medlineplus.gov/anxiety.html#:~:text=Anxiety%20is%20a%20feeling%20of,before%20making%20an%20important%20decision.
[3] https://www.webmd.com/brain/features/keeping-your-brain-fit-for-life#:~:text=Eat%20Well,brain%20healthy%20throughout%20your%20life.&text=One%20treat%20to%20consider%20adding%20to%20your%20diet%3A%20dark%20chocolate.
[4] https://www.healthline.com/health/happy-hormone
[5] https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/serotonin#:~:text=Serotonin%20is%20the%20key%20hormone,sleeping%2C%20eating%2C%20and%20digestion.
[6] https://www.medicalnewstoday.com/articles/320839#:~:text=Endorphins%20are%20chemicals%20produced%20by,surgery%20or%20for%20pain%2Drelief.