Periods delayed. Or breast tenderness.

My girlfriend and i had sex couple of times without protection 3-4  days before her ovulation day. And just after her ovulation day she had red blood drop in her mucous. That drops are very little as told by her and did not resembles to implantation bleeding as she searched on net. Now she is 2 days late with her periods date which is 15/12 and she is having cramps and leg pain. But no sign of pregnancy is existing as i asked to her.. She is also having acne and mood swings. Moreover she took i pill 1.5 months back.. In her last cycle which came earlier. Can you just tell what is happening is the matter of concern that her period is not coming or they will start in some days. She is absolutely normal as comparing to pregnancy sign like urination or breast tenderness.