I was working out on Friday which was the 19th of December 2014 when I told my friend to slap me as hard as he could in my face. I was pumped on adrenaline and wanted to get even more pumped with a slap. What I did though was underestimate my friend and he hit me hard as hell. He slapped the left side of my face with his right hand and I felt an vibration kind of going through my nose and the pain of the hit. I am not sure if he hit my cheek or his full palm slapped the entire left side of my face up to my head. My only concern is that every since then i have had a little bit of a headache. The day after he hit me i went to go workout again and vibrations were irritating my head so i stopped there. The headaches which arent really painful just more of an annoyance are on the left side of my head where i got hit. I was also reading symptoms of concussion and it said headaches and fatigue are a symptom which is mostly what i feel but just more of the headaches. I hope it isnt anything severe because it has been a full week since the incident and nothing has gotten worse im just wondering if its because of that or something else.