Help/opinions please!

So my last period started December 18th. I am on birth control pills (take them almost the same time everyday otherwise there is a 1-3 hour difference, never more). I’ve never missed a pill. So I had sex on dec 31st/dec 1st. He pulled out and didn’t cum in me at all. I’m worried about pre-cum though. Then on Jan 5th while still on my active pills, I had brown/dark red/pink discharge, and small discharge chunks when i would wipe. I kept getting nauseous and had mild cramps. I was worried it was implantation bleeding. I took a test Jan 7th and it was negative. However, I have been having this brown discharge and little bleeding for 6 days now. My placebo week for pills starts Sunday. Do you think this is just my period coming early, or implantation bleeding? This is what I’ve had the last 6 days.. I think I’m stressing myself out thinking that my pill may have failed and I’m freaking out!