Is Finasteride responsible for massive hair loss? I started it a month ago.

Hello, i am 21 years old and my hair loss started about 1 year ago. First my hair got thinner and then the loss was visible in the front and on the top head. I started with minoxidil but lost also 100 hairs a day. I started using Finasterid (Propecia) 4 weeks ago. Since two weeks i lose more and more hair (150-200 daily), you now even can see my skin. My question is now if I shoud stop with finasteride or is this a normal "shedding" effect? My doctor told me that there is no shedding.