Let me just say this...  If you are experiencing sudden and unexplained hair loss...  TAKE YOURSELF TO THE DOCTOR.  There are about a 1000 reasons for this ranging from stress to hormonal imbalances to kidney disease to cancer and it's up to your doctor to decide which one is your problem.  Because hair grows so quickly, it is often the first to feel the effects when something else inside the body is malfunctioning.  So if you're having this problem, please, for the sake of your own health, go see your doctor.