Implantation bleeding?? Help

Hi

Myself and my partner had unprotected sex 4 days in a row whilst I was in my ovulation window. Approx 6 days after this I passed some pink discharge then the next day some brown. Nothing went on my underwear it was super light. The spotting stopped then we had sex a few days later and I had a little bit of brown spotting again. It is now 2 days until my period is due but I feel nauseous and exhausted. All tests have been negative so far. I never ever spot normally, apart from the day before my period is due. Tia.