Blood Clots during Menstrual Cycle

After reading everyone's Q & A's in a similar section I feel kind of silly writing but I'm a little worried. For the last 3 months I too have been having large and frequent blood clots about the second day of my period. Same as with most there is cramping involved. It will last a day or two then it's back to normal. I am 30 years old with no kids, miscarriages, and I am not on birth control. What worries me is each month I seem to get weaker, feel more light headed, and the blood clots get worse. Has anyone been diagnosed with anything serious with my symptoms. I think this may be making me anemic.