I'm almost two weeks late, but took 4 pregnancy tests and all are negative

So here's the thing... I was around a week late for my period , I started taking pregnancy tests but they were negative , I took around 4 of them. But now I'm around 2 weeks late , and I've started producing thick brown discharge with a little pinky red colour (lightly). I've had other symptoms of pregnancy , sore breasts ,back ache and headaches but no sickness. Could I be pregnant?? I'm so confused