i really want to answer this bizarre question but struggle with trying to take your question seriously. first you did not cause brain damage from expelling gas unless the force of the fart launched you forward or into the air at great speed (see this what i struggle with! ). a sudden movement of the head or neck can cause a brief spasm of the neck muscles so i suspect this is what happened to you. i trust you have fully recovered and that there are no unintentional collateral damage to your physical surroundings.
my fart hurt the back of my head on the left side? . this is a stupid question but i farted and the left side of the back of my head started hurting for a few seconds. did this fart damage my brain or anything?