Old blood, wacky hormones, implantation?

I have been on the pill chateal for a year and I just stopped taking it. My last active pill was the 16th of August and I had my withdrawal bleed 20-26. Me and my husband had sex on the 26 and he came inside me 3 times that night / next morning. I had clear normal discharge the 27th and most of the day the 28th. I was surprised to see brownish pinkish discharge in my underwear the 28th evening. Today is the 29th and I I’m still getting it but more pink now. What the heck could it be? I’m thinking it’s just my body being weird as the hormones adjust, what do you guys think?