I am a 26 year old female who always had

Patient: I am a 26 year old female who always had very thick curly hair. I have noticed that my hair has been thinning over the years but never at an alarming rate. Now, about five months ago, I started noticing it falling out at a way more rapid rate. It is now so thin I can’t even wear it down. I went to the doctor and got my thyroid checked and it was normal. I am on birth control but that is it. What is causing this?

Doctor: