Implantation Bleeding?

What's your thoughts? I always have a 28 day cycle. But yesterday was CD25 and in the morning when I wiped there was a slight pink tint to my CM. thought nothing of us really bc then nothing the rest of the day till my husband & I had sex. As soon as we finished he asked if I had started my period, except I don't have normal period cramps and it wasn't red blood it was pink again. This morning when I wiped it was brown like old, and now (this afternoon nothing really). Any ideas on what is going on? Please help!