What Are The Side Effects Of Using Intrauterine Device?

My cycle usually comes on time every month...I had a normal cycle (from what I can remember) on June 05, 2010...my cycle started on June 30, 2010 but it only lasted one day...no cramps or bloating before cycle...the cycle wasn't normal at all...started at 9 pm and was over with by noon...it was light red almost pink...since then I have been nausiated and moody and feeling bloated...no breast tenderness or swelling that I can see...took two hpt and one blood test and all 3 were negative...could I still be pregnant but it just isn't long enough from the (what I would call) implantation bleeding to show up?