What Causes Fluttering In Abdomen And Vaginal Bleeding Along With Clots?

I have had 2 children, and am now experiencing similar "flutter" and "flicking" feelings as I did when them. My bra feels tighter and my appetite has changed. About a month almost 2 months ago I had the same feeling a and took 4 pregnancy tests I got 2 positives and 2 negatives, then started bleeding with excruciating pain, bleeding was mainly huge clots. Any idea what could be going on?