What happens if you blow air extremely hard with your nose, mouth, and ears covered?

[eneceledus]

When I was 12-13 I was running fast in the hallway at school. I dropped my lunch box outward and while running I bent over to attempt to retrieve it and with my head tilted down I hit my head on the corner of a wall hard. I then had a big pool of blood about a few feet wide on the ground. I lived up in the Rocky Mountains and was taken to a small clinic there and they only gave me stitches. No ER room, no tests. The scar is about four inches long.

When I was 14-15 my friend told me to sit upside down on my head on a couch, push and blow air into my head as hard as I could while he held my ears closed, and I held my nose and mouth closed so the air had nowhere to go. I pushed as hard as I could over and over for a few minutes with not having much room for the air to escape.

Since I am not there, hypothetically speaking what kind of damage could have occured from all of this? I've heard others online say things like herniated sinus, damage to vagus nerve, cranial damage, etc. I've also heard people say its just anxiety or I'm over reacting, but my eyes become bloodshot after bending over, that's a direct physiological response, I don't just have anxiety. Could my brain be swelling for some reason after bending over causing the red eyes? I would like to know what to tell the doctor or what kind of tests I should have. I'll be seeing a physical therapist in a month for my back, I'll tell him about the head or nasal issues.

Symptoms:
These can last the whole day, part of the day, or a short time.
When I bend over forward or tilt my head too far (other triggers too see below) my eyes become red and burn, vision a little blurred. I feel pain somewhere I think in my nasal cavity. I feel like there is some kind of unequal pressure in my head and pain as I move it around like my brain is swollen or it feels like I have painful moving slight water logged head. It becomes a lot harder to think, foggy thinking. I have difficulties remembering things. Decreased cognitive ability. While its happening I have a lot less energy, my heart feels stressed if I try to run while feeling like this, I feel a throbbing sensation in my fingers and other places. Sudden or inconsistent sounds and or lights feel like they are "grabbing" at my heart or cause a little pain in my head. Some kind of slight epilepsy? (I also had a head injury a little before then see below) I think I've had a couple of small seizures. I feel like I need to keep my head as level as I can and can't tilt it past a certain point. When my eyes turn red I also feel a strong sensation of my pulse at the tips of my fingers and increased awareness of my heartbeat, but the doctor says everything about my heartbeat is normal. I feel a throbbing sensation in other parts of my body too.
Also when laying down I get tiny air bubbles that trickle out of one of my nostrils making a tick, tick sound, even when I hold my breath, doesn't seem to be coming from my lungs. Not sure if that's related. When it goes back to feeling mostly normal and I feel better, my head still feels "not solid" and feels like I need to avoid bending over. I think I've also had a couple of small seizures, I fainted once in the bathroom and when becoming conscious again it was like my arms were locked together.

Symptom Triggers:
Some are stronger than others.
Pushing when pooping or farting. Tilting my head too far. Bending over. Breathing through my nose or blowing my nose. Swallowing. Sucking. Sneezing. Also sudden or inconsistent sounds or flashing lights feel like they are "grabbing" at my heart or cause pain in my head.
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Now years later with a possible back injury, when walking I feel pain in my heels (does not radiate throughout legs) each time I feel pain in my heels I feel a corresponding pain in my head. It seems like Sciatica from what I've read, except Sciatica doesn't radiate to the head. Rolling my heels slightly, or being on uneven surfaces feels like it pinches my heels and at the same time causes a pinching pain feeling in my head and each step triggers some or all of the above symptoms temporarily or for longer time.

Not sure if this has anything to do with it, I didn't feel different after this even, but also when about about 10 years old I was riding my bike in the street and I got knocked out, I remembered something about a lady saying something like "Its your fault!" I think I got hit by a car. I came home, later people told me for a few hours I didn't know who my family was and then I went to sleep for a few hours and woke up normal. They didn't take me to the ER or doctor for that either. I had scrapes on my body including my head. No scar or stitches from that. Broken bike though.

Considering all of the above, I have many symptoms and many theories. Could part of my brain be getting pinched in a crack in my cranium? Could my brain be swelling for some reason? Could I have a hernia in my nasal cavity somehow? How could that affect my brain?
What connects my heels to my back and my head? I'm not sure.