Injured back 6 months ago working out. haven't got over it yet. now they are saying it's facet joint arth. can it spontaniosly happen like that? im 22

Facet Arthropathy: Yes it can happen if you injured those joints when working out. There are joints in the spine where the bones articulate and can develop bone spurs and cause pain typically with extension movements or injuries. I would consider seeing a pain/spine specialist to see if facet injections or radio frequency ablation would be helpful for you.