Blood test!?

I tend to worry about my health since the birth of my son! it gets worse when im alone so i have recently got a job to try to take my mind off illness! ive been refered to see a councillor and although i know this is ridiculous i cant stio worrying im gonna die of something very serious too early (im 19) i had a blood test, as i was worried over certian cancers kidney disorders why my hair was falling out so much and why i suddnely got bad cases of IBS, what would a blood test show up? i have an ache feeling in my left middle to lower of my back and it is worrying me but i dont want to visit the doctors yet again. please help