10 dpo and brown discharge?

Chelsea

Cycles are normally 30-31 days. AF not due until the 27th. Took a test with fmu and got a bfn but when I wiped I noticed light brown discharge. I normally spot 1 day before period. Is this AF coming early or implantation bleeding? other symptoms: sore boobs since 4 dpo, vivid dreams, waking up throughout the night.