What Causes Light Followed By Heavy Menstruation After Receiving Methotrexate Injection?

I received methotrexate injection after finding out that I had an ectopic pregnancy on January 29, 2015. I began having light bleeding 5 days post the injection for about a week and a half and then it stopped for about a week and began again heavier 2 days ago. Is that normal or should I go to the emergency room.