What Causes Dark Clots Like Bleeding During Periods?

I am not on my period and I have been having constant bleeding for over 7 days now. Not blood like a period but blood clots and bloody long strands of what appears to be skin type material and pieces that are a dark black color. The blood doesn't come out like a period either it is very thick. I have had pre-cancer cells do to the HPV virus about 5 years ago but have had a clear pap the years following. I am going in for my pap in the morning since I haven't had one in a year. What could be causing this irregular bleeding and clots. I am scared and just wanted a second opinion. Thank you for your help in advance.