10dpo?

I’ve been feeling a lot of twinges in my right side on and off since 6dpo; last night around midnight I got just a hint of brown discharge. This morning there was no discharge in my underwear, but there was some when I peed and when I wiped. It’s still 4 days before AF, I had a bbt spike first thing, and my boobs feel like rocks. But I got a BFN when I tested. Could it be implantation bleeding and I just need to give it another couple of days before I test again? I had implantation bleeding with my first pregnancy (ending in a miscarriage) but that was years ago and I’ve blocked out a lot of my memories around that time. My abdomen also feels kind of fluttery, but not the intense cramping I typically get at the beginning of my period.