Could Discharges, Bleeding, Cramping, Back Pain Be An Ectopic Pregnancy Or Miscarriage?

I had a positive pregnancy test and should be 4 weeks. The past few days Iv had a brown discharge and this morning it was a slight bleeding. I only cramped slightly but as the day went on my lower back started hurting soon becoming unbearable. My left side hurts unbearably too. I bleed slightly all day but not enough to fill one pad. Could this ectopic pregnancy or early signs of a miscarriage? I have had 3 previous miscarriages one resorting in a D&C. All of my blood work has been fine and the tissue from the D&C was also fine.