Recently for about three months, my periods have been weird where it is heavy for about a day then really light for like 2-4 days. This recent one has been the longest of my periods and today is day 5. Today when I took out my tampon out it looked like this. It's really dark and I always have really bright blood, I haven't had dark blood in years. I don't know what it is and I am a little concerned. Any advice helps.