I Have Only Been Getting My Period For About Five

I have only been getting my period for about five months and am not due for another few weeks. However, I was using no the restroom today and found a piece of tissue, not unlike what I have seen during my period that was about the thickness of two or three wives of yarn and about six inches in length. I have recently gotten my hands on a divacup and did a "dry run" with it just to get a feel for how to insert it, remove it, etc. I noticed minimal bleeding when I did this and when looking it up, it seemed normal. I have also been feeling lightheaded and weak all day and some of yesterday. Should I be worried?