Tree Fall Causes Concussion

I was climbing this tree and lost my balance. When I lost my balance my weight went on a weak branch which then gave way and I fell and landed on my back. When this happened my head kind of had a slingshot effect and I blacked out for a few seconds. I actually don't remember saying anything until I say WTF just happened? Then the rest of that day and most of the next i would forget what someone just told me 5 minutes after they said something.