What Causes Numbness In The Arm?

Two days ago I was experiencing bad diarrhea. The next day I developed what I call a head cold but of course I am not a doctor. I have a lot of sinus pressure, I went to sleep and woke up to both of my arms being numb. It went away for a bout an hour but now I have a really strong numbness in my left arm. could this be caused by the "cold" or is this a symptom of something more serious?