its almost 9 days now that i received a blow on my backside of head by the cupboard door ..it was a hard hit but i did not pass-out or paralyzed one side or did not feel any problem in talking or concentrating..nor a bump or bruise .i mean i did not feel any symptoms of brain injury ..but after 2 days i feel pain in skull when i touch ..is this something serious or it will go away by itself ??