Brown spotting but no proper period

Two days ago I started to have very very light spotting. Just occasionally when I wiped I found some pink streaking that turned brown yesterday. Today I was expecting AF to begin. In the morning I though it had but it never actually turned into anything. Just continued with very minor brown spotting. This is very unusual for me. Has anyone else experienced this? Should I expect a full period flow? I ruled my self out for this month but I took a test today just to make sure and it was negative.

Thoughts?