What Causes Continuous Spotting,hard And Round Stomach And Mood Swings?

i have had the iud in me for 2 years now. ever since i had my son. At first I had my normal periods once a month for 3 days a month. then it moved to one day a month. then suddenly I started bleeding everyday all day. Its enough to fill a pad about once a day. It went on for months without ending, then suddenly it stopped except for some spotting. The spotting still wont go away. now my stomach got very hard and round, I have mood swings and my appitite is gone. I do practice un-protected sex except for the iud. what could this mean?