My last two cycles were on January 5th and January 31st. My menstrual cycles have been regular for a long as I can remember. The cycle that started on January 31st ended on February 5th. On February 11th, I saw very light spotting (pink and brown). It is now February 13th and I am still spotting very lightly. Does anyone have any explanations?

IF it were implantation spotting, it would not last for several days. Spotting can happen for many reasons so you may want to call and mention it to your doctor.