What is this pain

Every time I get hit any where I feel like I’m going to pass out and I feel nauseous. It lasts for about two minutes and goes away. But I had to sit cuz I started seeing stars. It happened to me yesterday at work when I hit my elbow really hard, and another time when I fell upstairs and hit my knees hard on the metal steps.

Also when I get hit some where like in my sides I feel like I’m on fire, feels almost like if you would have a body part fall asleep.

I’ve tried looking on google for answers but I can never find anything. Anyone have any idea?

I’ve also noticed some times I’ll get wide spread pain in my Lower back up and through my shoulders.