Implantation bleeding

I am unsure to whether I have my period or implantation bleeding or normal spotting. I normally have a 30-32 day cycle but this month it has been 28 days. I started this bleeding yesterday (11th October) and my last period was the 13 of September. I took an emergency contraceptive the day after I ovulated around the 27th of September as my boyfriend and I had unprotected sex but he did not ejaculate inside of me any of the times we had sex. I am just wondering if this still could be possible implantation bleeding as the bleeding is light but is mainly constant bleeding and I have severe cramps. Could it be the emergency contraceptive I took causing my period to act different or could I be pregnant? I have been bleeding since yesterday.