Sore back of neck and back?

today i woke up and the back of my neck feels bruised and sore ..it hurts so bad..right when like my head ends and my neck starts. also my back has the same pain in it..in the uppper back. yesterday iwas sitting on the floor for a few hours kinda slouched over looking at old pcitures. could this have caused a pain today? iam 18. i am really scared its something bad . also for the past like week i have had t his weird buzzing/vibrating feeling in my left hand..mostly in the thumb, pointer and middle fingers. with my luck i hit an area close to my funny bone which made the rest of my hand numb and that area hurts to. does anyone think that could have cuased my neck and back pain? i really hope not b.c that seems serisou..im hoping its from sitting weird..does anyone else have that happen to them>?