Brownish discharge

Jasmine
Hello,
I have a quick question. We did a test at home and it came out positive for all 4 times and once with the doctor. I'm around 4 weeks pregnant. I started getting brownish discharge this afternoon and I tested again but it's very faint. 
What can this possibly mean? This is my second pregnancy. Had a miscarriage with the first which resulted as ectopic pregnancy in May. 
I would greatly appreciate the answers.
Really worried and stressed:(