Why chew the cud?

Sick and tired of going through the endless cycle of wondering why I ruminate. I've been having this issue since I was young but about 3 or 4 years back, things became harder when I started having random thoughts on why I ruminate. To make matters worst, it escalated in the middle of last year and once, I even had a migraine for 3 days.

Kept telling myself not to look back or keep questioning why but it seems so hard and I kept having to go through the same thing over and over again. When will it end?