Discharge

Ok ladies , I'm 38 yrs old . I have been having a brown discharge since Tuesday .. My cycle is due to come on Saturday , mind you I've never had this to happen . I have not been sexually active since October of last year . Today I wiped and there was a good amount of blood . I'm confused . I am on BC and recently been taking pre natal vitamin for my skin and hair .  I called to make a appt with my obgyn but no avail until may . Please help if anyone has an idea on what this could be other than my cycle