Growing up my hair was so thick when I braided it, it was the size of my fist. Now, within the past year, it has thinned out so much a braid is only the width of my pinky. Does anyone know what could be causing this to happen? Or what I can do to reverse it? I have been using Mane-and-Tail shampoo and taking Vitamin B supplements but it has been getting worse. When I put my hair in a ponytail I actually can see bald spots. Please help me.

I’m a 24 year old female.
Full Time Student (no health insurance)
Well balanced diet (I cheat only once a week)
Diagnosed with Chronic Migraines.
Currently taking Tri-Sprintec(birth control)
Fioricet and Sumatriptan(for migranes)
No history of hair thinning in my family(not even the men!)

Please help me.