I'm having a month long period. Why?

Okay, so I recently posted a question about missing my period for like 3 months. Now I've finally had one naturally and it's been going on for about a month now. I'm curious to know if any of you have ever had this? If so, did the period stop naturally or did you have to visit an OBGYN? FYI: I'm going to an OBGYN with this problem, I'm just curious if anyone else has ever experienced this?