spotting

I need some input! I had my period on the 1st September lasted 4 days which was great... on the 16th sept I had some brown/red discharge but stopped after 2 days was not heavy at all then on the 28th around 2pm I had brown discharge but it's not constant or heavy I can go from 5pm right through to the next morning with no spotting... I am currently 10days dpo and due AF on the 3rd October I've succumbed and took a test today but came back BFN anyone any idea what's happening? I'm hoping this month is my month 🙊