Hello Dr. I Used To Have Very Regular Period Since

Hello Dr.
I used to have very regular period since I got married last November, however, I start to take Duphaston 10 since last two months as per my DR advise. in the first month of usage I got my period on time but this month ( I suppose to get it on 1st ) there is delay of 10 days and I have urine test for pregnancy 8th of this month but it show negative. but yet I dnt get my period but I start discharge of brown color. please advise that this discharge is sign of pregnancy or its my period which due to usage of Duphaston it turn like this.

Thank you