I have been on Ortho Tri Cyclen Lo for about 5 years now. My period has tend to come during the 4th day of the placebo week. Today is the third day, and I had some spotting about the size of a quarter that was a light redish color which I had assumed was my period. I put a tampon in thinking this was my period and found it dry hours later. I had sex on 5/10 and then about 5 days later I took my pill 18 hours after I normally do as I forgot the night before. I also had sex two nights ago. I've had some cramping, and my breasts are sore, and acne as I usually have when my period is approaching. Could this be implantation bleeding?