What could be causing me to have occasional cramping and spotting on cycle day 8 of my menstrual cycle? i'm 43 years old?

If "day 8" represents eight days after a regular menstrual cycle, and your period was heavier than normal, a clot could block the cervical canal, and uterine contraction may cause pain, and spotting instead of continued flow. At "age 43",not on oral bcp's, the endometrium is thicker , and bleeding can result more often in clot formation. See your GYN physician for guidance.