My period cycle is generally 28 days each month. This month it came 18 days after my last period. It began with brown spotting for two days, then a light flow of dark blood. I am still bleeding after 5 days (normally my period lasts 3- 5 days). Prior to this happening I have experienced a great deal of stress and I had a hard knock to my abdomen surfing a day before the spotting began. Should I wait it out to see how I go next cycle or investigate further with my doctor?