Interesting...
I experienced a change in time that wasn't a flashback but more of a shift from one timeline to another.
I was driving home from work one night around 2:30 am when I felt a sharp snap in the right side of my head. Luckily I was only moving about 30 mph on a deserted street so I safely pulled over.
The snap felt like I had been shot but there was no blood and no hole and the pain subsided quickly.
At that time in my life I was happily married, fairly healthy and in shape, the kids were graduating high school soon. Things were going pretty good.
Soon after that night things started going downhill. I got hurt, got sick, lost my job, divorced my wife, became disabled and so on, rather quickly (a few years).
When the snap happened I noticed what felt like a shift sideways in reality.
At the time I was like "hugh" but as these things in my life started changing it occurred to me that I might no longer be in the same reality I once was. It is like I jumped to another timeline. I can't even be sure that the memories I have now are the memories I had before the snap.
I had a CT Scan and an MRI done on the right side of my head, expecting evidence of a stroke but they found nothing wrong.
If simultaneous dimensions exist, where did my original timeline go? Is there another me with my old timeline? Do I have another me's original timeline? What happened to that me? Did it die? Did we merge?
I often wonder if it will happen again?
I have lost a lot of people in a few years time one after another and due to their passing I broke down in 2013 at age 17. I had a derealization period for 3 days. Was very scary. Like the world around me felt unreal.
My eye sight also was severely impacted. It subsided after 3 days.
Was a very very scary experience. I cried so much in those days. A psychiatrist concluded that it was my grief for the ones I loved, combined with my gender dysphoria ( it was before I transitioned ) that caused this.
I never want to experience something like that.
Derealization is very common in people.
Could that be what you experienced?
Benzodiapamines helped me during those 3 days.
What I 'felt' was a snap. The physical effect was quick and subsided quickly. Like a rubber band snapped against a table.
The effect was my timeline was pushed off like a Newton's Cradle with no return reaction.
Imagine this action without the wires. My old timeline flew off and was replaced by the next one.
It 'felt' like reality shifted to the side and was immediately replaced by another.
The closest analogy is the premise in the TV show "Sliders" but the changes were of a personal perception instead of environmental.
I have since done some research and found that there is a theory that we make all the choices of life and each choice results in a different timeline in a specific dimension. Like in one dimension I had eggs for breakfast and in another I had cereal and in another I had waffles and in another I had nothing at all for breakfast.
All these dimensions exist beside one another separated by the different choices we make. Dimensions with little difference are close together like shades of color.
What this felt like was a snap realignment of a distant shade.
It sticks in the pit of my center and I've felt something was off in my timeline since. Its been over a decade and it hasn't subsided.
Like a locomotive that suddenly jumps to a side track five or six tracks over.
From time to time I still get a dull pain in that same spot in my head.
I thought it was a stroke but strokes leave evidence and nothing has ever been found to suggest a stroke. The Doctors have looked.
When I experienced the snap, I also heard it as a loud ringing. My vision went sideways and my body tightened. For a split second I was incapacitated but it was over so fast I didn't lose my grip on the wheel.
It was like something impacted me on the side like a giant jab or punch.
The longer I move away in time from the event the more my timeline feels changed. I remember driving the rest of the way home, I knew something was different about me but I couldn't put my finger on it. A little more than a decade later and I sense two timelines in my past. I also sense that both are accurate. Its not distressing, its perplexing.