I've experienced the dizziness like you describe. For me it was overstimulation, like crossing a busy street where there were so many cars moving so fast it was a big chore for my brain to process.

What causes the dizziness? Lower your activity level to avoid the overstimulation. As your condition improves, gradually increase your activity level.

Inflammation also causes concussion symptoms, which means you can experience concussion symptoms without a concussive-force impact. Chronic low grade inflammation contributes to anxiety, and the anxiety feeds back creating more inflammation and more symptoms. So it's important to relax and also take steps to reduce inflammation.

The shoulder incident may have caused a neck injury, which can cause concussion symptoms, so seek treatment like soft tissue massage.