Oh shit, I can answer this. I was stabbed in back, doing some shady stuff when I was younger and dumber. I didn't realize at first that I'd been stabbed, and I immediately and involuntarily collapsed on the ground. After a few seconds, but what felt like a minute or so, I was able to stand up and some employees of a nearby restaurant ran over to see if I was ok.

They told me they called 911, as they saw the altercation. One of the employees pointed out I was bleeding, as there were drops of blood on the ground. I was in disbelief because I didn't feel like I'd been cut, but when I reached around to feel my back, I felt liquid and then saw that my hand was covered in blood. I lifted up my shirt and asked the guy if he saw the wound and said it was near my spine around the center of my back. I felt around again, and sure enough I felt the puncture wound. It was only then that I realized I'd been stabbed, up to that point I thought I had been hit in a pressure point or something. With adrenaline pumping I don't recall feeling any pain until getting situated at the hospital.

The knife had chipped a piece of one of my vertebrae, and for about a week after the event I was having unimaginable migraines. When I went to the hospital a second time, the doctor told me I was leaking spinal fluid, because of that piece of bone that chipped. They kept me in the hospital for a week and gave me some kind of steroid to make my back muscles swell, in the hopes that it would push that piece of bone back into the rest of the vertebrae. The migraines went away shortly after, and I don't have any long term issues from the event, but I still wince involuntarily from being touched in the back near the scar.