What Causes Dull Pain At The Back Of Head With Numbness In Fingers?

ok so I have been having this dull pain in teh back of my head almost behind my ear but at the bottom of my skull. It lasts for a few seconds to a few minutes. but lately it has moved to the other side. and I have been having dizzy spells and nose bleeds I have also had trouble remembering things. The pain usually occurs more at night. and I have a hard time sleeping. I also get bruises and dont know where they come from and my fingers will go numb. is there any idea as to what this could be?