Implementation bleeding question

At around 9am this morning I went to the bathroom wiped and saw bright pink. I put a tampon in thinking my period started. Usually when I get my period it comes in full force. At 11am I went to change it and the tampon was clean. Same at 1pm when I changed it. My period is expected tomorrow. I didn’t really track but based on my cramps and ewcm I’m currently 12 or 13 dpo. What could this be? Should I go buy tests because I’m out?