Can this happen?

Can you get a positive hpt before implantation occurs? I went to the doctors Monday and got a positive urine test there as well. But for the past 3 days now I've been having this tanish color discharge and light pink discharge. No bright red blood though. I haven't been having a cramps or back pain. And I still have pregnancy symptoms. I'm 3 weeks & 6 days today. Could it be a m/c? Im just so worried and confused right now ): I need to put my mind at ease. Has this happened to anyone?