A few nights ago , we were sitting around watching a movie . I pulled a shard of bone out of my mouth . I had a tooth pulled a month ago or something , and the wound was still giving me some pain until Sunday , when I was sitting on the couch , tonguing the place where my upper left molar once was ( this has become a habit ) , and felt something like a splinter poking out of the gum . After a few seconds of probing , I spit out a jagged little piece of bone .

Question: Why is the narrator walking around with so much pain ?
They have a mouth injury .