I have been losing my hair catastrophically for a few months now! Should I take supplements and which ones?

Considering your age, it is possible that your hair loss is hormonal in origin. If the hair loss is sudden or patchy, I recommend that you see your doctor. Taking vitamins will do very little to help your case. Two pharmacological treatments that are considered effective in a case like yours are minoxydil/Rogaine and finasteride/Proscar or Propecia. Minoxydil/Rogaine is a gel that is applied to the scalp twice a day and left on for a minimum of 4 hours per application. Finasteride/Proscar or Propecia appears to be quite effective, but can cause decreased libido and erectile dysfunction in some cases.