Hair Breakage

Patient: I have always had thin, fine hair. I have ben taking supplements and vitamins (B complex, biotin, etc) for over a year and have noticed that my hair breakage at the ends has stopped. However, my hair is breaking like crazy at the crown now. I have been doing everything obvious (changed products, etc) to help this. I have had my thyroid tested many, many times over the years (had infertility issues – miscarriages) and my thyroid functions have been normal. Less than 2 years ago I was tested again because I was feeling extremely anxious and was having heat intolerance and my levels were normal. I take Singulair, Simvastatin, Xyzal and BC pills. I am 47 years old, thin and in great physical shape. I exercise regularly. Could one of these medications be causing my hair to snap off?