Why would my doctor prescribe a prenatal without telling me if I'm pregnant?

I checked myself into the hospital for personal reasons, and upon release on Friday I was told my vitamin levels were low so I would be given vitamin D3, B1 and folic acid. I went to pick up my prescriptions today and was given a prenatal along with the vitamins seperately.

I was not told I was pregnant, I had one day of heavy bleeding yesterday and today I am not bleeding at all whatsoever, not even leftover blood. I'm very confused, why would a doctor prescribe a prenatal to someone who isn't pregnant, or why wouldn't they tell me if I was?