Two periods, one month

Emily
Hey ladies,
I'm 20, so my period has regulated itself throughout the years. However, it has always been very heavy and very painful... not to mention long. Often it would span about 7 days with heavy flow the whole time. Now, it only lasts four days with an incredibly heavy flow (new Super + every hour). 
Then, about 5 days later, I get another period! Two! It's thin and dark red/brown, but it's way more than spotting. 
Has anyone experienced this before? I'm going to the gyno soon, but I'm just so confused by this. 
Thanks in advance!