brown/bloody discharge help ?

I am suspected endometriosis however last week I started to get brown/bloody discharge I thought I was bleeding at first becouse it was quite a lot but it's not constant so realised it was discharge this started last week about 2 week before my period is due I also have abdominal pain I haven't had this before can anyone shed any light please ? I'm still getting it now approx 6 days since it started ? Any advice much appreciated x