Still spotting

For the past two months after have felt pregnant. Tired, cranky, hungry, sore boobs, the whole shebang. However I have not skipped a period and I took two tests that turned out negative. This month I got my period on the 20th. My period usually only lasts about 4 days, but as of today, the 27th I'm still spotting. It's really weird and out of the norm for me. It's also accompanied by some mild cramps. What could this be?