I Had Redish Brown Discharge 1 Week Before My Period

I had redish brown discharge 1 week before my period was due, then my period didn't show when it was due so I took a test, it came out positive. It has now been a week after and I went to confirm at a pregnancy center and the test said negative. I'm confused. I have been bloated, tired, nauseous, headache and backache. I have not had any bleeding but cramping very slightly since the discharge. What do you think I should do. If I'm pregnant I would be 4 weeks4 days.