The brown discharge is due to the fluctuation in your hormones. This difference in hormones often symbolizes the lack of ovulation.
Pregnancy test are 99.8% accurate when used correctly. However, it is recommended to always confirm the results of a pregnancy test with your Doctor because home pregnancy tests are good in detecting the human chorionic gonadotropin (hCG) hormone, but blood tests are more reliable.
Hope this answers your question!
REFERENCE(S)
1. The Answer Spot,
Period with brown blood and no red blood(Online: Oregon State University, 2006)
Period with brown blood and no red blood : SHS AnswerSPOT, Oregon State University
2. Ann Linden, CNM,
Home pregnancy tests(Online: Baby Center, 2006)
BabyCenter -- Pregnancy Tests: Are home tests accurate?