Help- pregnant again?

Hubby and I had post partum sex after 6 weeks. On Saturday I noticed just a tiny amount of Brown spotting. On Monday I had some cramps and today I’m noticing some cervical mucus. I started probiotics on Friday - I’m hoping my stomach issues are just my body adjusting to them... anyone have similar symptoms and end up pregnant? I’m so worried. I took a test on Monday and it was negative. Is there still a chance?