got this dark brown discharge can i be pregnant?

Ok so my last period was 20 of february it was due 20 of march, but I never got my period in march so now 6 of april I got this dark brown discharge and I still got it, I don't know what it is, but I don't get red blood all it is, is dark brown, I read somewhere that you can mistake vaginal bleeding for period. Is it normal or am I pregnant and don't know it