What Causes Hair Loss?

Hi, I am a 24 yr old female from Bangalore. I have been facing hair loss and hair thinning issues. I was put on spironolactone and yasmin for a year since i was diagnosed with mild pcos although i did not have severe symptoms but had a few acne. During this time, my hair strands thinned out. I stopped taking these tablets in jan 2015. By april 2015, i had severe hair fall and it has not yet stopped. Soon after i stopped these tablets, i got my blood tests done for ferritin and vitamin d. My ferritin was 10 and vitamin d was 3. I took supplements orofer xt and drise and currently my ferritin is at 27 and vit d at 57. My hair is still falling out and I lose around 150-200 hair daily. What could be the reason for this? The hormone tablets already caused hair thinning and reduction in volume and now there is hair fall as well which makes my hair look much thinner. I have always had thick black hair and now my hair strands are thinner and brown in color.