Hi, Last Month My Period Ended Earlier Than Its Normal

Hi, last month my period ended earlier than its normal 6 days (lasted 4), and about a week later I went for like a hard run and started cramping badly afterwards, and started having light bleeding as well. (This was around ovulation) Ever since then every other day I've had very light cramping and light spotting. Today, two days away from my expected period, I've discharged brown stringy blood clots. I feel fine other than feeling a little tired from going to school, work, and practice, then studying. What could this be cause I'm worrying about it.