Hi... The way you have explained, it seems you are suffering from cognitive anxiety caused by overthinking or by your natural way of going through life.
Following a healthy routine in terms of proper and timely meals, sleep, exercise, breathing/meditation will help you get back your control over your thoughts.
If you have developed some maladaptive coping mechanisms overtime they need to be fixed through psychotherapy/counselling.
Next Steps
Seek Counselling/Therapy from a Psychologist. To Seek my Services Online you can Google me or visit my Website (https://gunjanmaithil.wixsite.com/therapy)
Health Tips
Practice any Breathing Technique (Deep Breathing, Alternate Nostril Breathing) daily for 20-25 min. morning and evening. Start any Physical Exercise/Sport daily for 40-45 minutes.