Why Am I Having A Bloody Discharge After My Menses?

I had my period 2 weeks ago. It began on may 4, 2011 and ended on may 10, 2011. Now for the past 3 days I've had spotting. First day when I I wiped after using the bathroom I saw hints of blood on the tissue. Second day I had a very small stain in my underwear of blood. And today I have a large brown gooey discharge with blood. I am really nervous about what it could be. Please help!