Gideon,

Welcome to NeuroTalk.

As Jo*mar said, Did you impact somehow?

Your first paragraph is incomplete. "so my head and neck have suffered the most, "

How did they suffer?

Was this a whiplash like stress?

Or, a vertical compression?

I suffered a vertical compression injury. It messed up my upper neck. It caused inflammation that, when at its worst, cause autonomic nervous system dysfunction (heart rate, blood pressure, breathing) and cause brain fog. All I did was step off an 8 inch curb and land with my knee locked and my back arched. Ouch.... Jarred from my pelvis to my head.

A physical therapist with very special skills (not range of motion and strengthening therapy) used myofacial release and similar pressure/trigger point therapies to get muscles to release from spasm (cause of headaches) so the joints in the neck could become mobile. She also did gentle traction and mobilization.

The most important part was my posture when resting or sleeping. I had to maintain good straight head and neck posture so the ligaments would not be strained.

The joint at C-1 to occiput (C-0, skull base) tend to not like these vertical compression stresses.

There is also a though that one can suffer a brain stem concussion by a vertical impact of the brain in to the brain stem.

Either way, the goal should be to reduce inflammation.

I iced frequently and took anti-inflammatory meds (enteric aspirin that does not cause stomach upset)

These injuries do not show up on imaging studies. They are more of a treat and see if improvement happens.

So, focus on inflammation and your neck. Give it a rest.

When I hit the concrete(very hard) my head was completely tilted backwards(from the gravity), and somehow I felt the blow up in my head, like the force went up my spine and legs.

Then I felt very bad in my head, not exactly pain more like nauseous headache, and entire neck being electrified.
I don't know about whiplash or vertical compression I'm not familiar with these terms.

And I did it over and over like 5 times, ignoring the outcome

I would assume you have been doing these hand springs for quite some time. Handsprings take a lot of practice to perfect. You likely have been wearing out these cervical joints. The head back position puts the spine into a straight line which takes all of the impact absorption out.

You may have given your brain a good shaking but it sounds like you surely gave your cervical (neck) spine a rough time. The joint between the skull and C-1 vertebra has no tolerance for impact. Jamming it together can cause the nerves to be traumatized. This can be dangerous.

80% of concussions have an upper neck injury component that causes concussion like symptoms. It sounds like you got the neck injury part of the trauma.

Vertical compression is pushing the two bones (skull and C-1, C-1 and C-2) together. This can bruise the surfaces. Whiplash is straining by using momentum to put joints at the limits of their range of motion.

You need to find a therapist, sports trainer, or such who can help you understand these issues and terms and the mechanics involved. They are rather simple concepts.

You should not be doing any more gymnastics until somebody has diagnosed what happened.

Did you learn handsprings on a gymnastic track that has give and then moved to a hard surface?

I used to do handsprings in the past, and all I can say is that performing this at hard surface was a huge mistake, just as the many other mistakes I did.

40% of my headache severity was gone 3 weeks ago(3 month after this all began), but I'm still dealing with some other aspects of it, especially pain around the eyes, tension headache, and surprisingly I had head related severe fatigue only once or twice, which disappeared after running 6 miles.

Ever since my cat scan went out fine I'm afraid no therapist would take my complaints seriously.

Great to know you're here for people who need help and advice

Recently I'm dealing with severe dizziness/lightheadedness,
shows up when I'm tired, and when I'm visually overwhelmed, like doing an exam, or when I drive. also it takes time to focus my right eye, especially at distances.
Cant keep my both eyes focused on objects.
Feel fatigue at noon.

Each time I would feel alot better after some sleep, been that way for at least 4 months since ny accident.
headaches and nausea sometimes.

I went to an opthalmologist who didn't find any abnormalities
What specialist could help me,
also could that be related to my neck/head injury?