Hi, i am now pregnant with my third child. It is a sign of possible pregnancy, the breast soreness/tenderness. Was your period lighter/heavier than normal? How close to your normal period (time of month)? I had a one day "period" about a month-and-a-half into my pregnancy, according to my calendar. Keep track of your periods that way, it makes it easier to tell. Are you nauseated, or more tired than usual? A lighter "period" may have been "spotting", which is common and usually no cause for alarm. Heavier than usual and maybe it was a miscarriage...I've never had one so I wouldnt know firsthand what to look for, or what it feels like. I would get a pregnancy test done asap, and see an ob/gyn. I hope this helps you, and good luck!