What's going on?

So I have really long periods that last 7-14 days. I'm recently on day 13 & my period isn't usual. Usually days 1-5 are light to regular flow followed by days 6-10 which are heavy & then 11-14 that rand in spotting. Well this period stared with Browish black blood & it has been regular nothing less or more. I've also been have an extremely number of clots, most of what comes out are clots actually. I've had a few before but not like this. Can anyone ahead some light on this for me?