What Causes Hair Loss?

I have been tested in a none fasting blood test. My liver enzymes were high-no hep B or anything like that, my glucose random serum high and my neutrophils, absolute low...but in the past month I have been loosing daily amounts of hair that is not normal. My thyroid tests fine, I went through menopause 5 years ago. I eat well, exercise some, take vitamins and have changed nothing at this point in my routine or diet. I am getting really worried. My doctor says it is fine, probably seasonal, but there is something wrong, I know my body.