Ok, I started my period on Oct 3, fooled around with my boyfriend a bit with a tampon in the next day while I was heavily bleeding. The following week, Oct 11, I had protected sex with my boyfriend (the condom didn't break) and then two days later I noticed a drop of blood on my underwear and went to wipe and there was a little bit of blood that quickly stopped the next day and hasn't returned. What does this mean? This has never happened to me before and I'm not sure if an egg could implant that quickly, or it is just my cycle changing. :-(