My Period Is Usually Every 21 Days Lasting About 5

My period is usually every 21 days lasting about 5 days. This past month it lasted 8 days and then returned a week later with cramps and large blood clots. I have had menstrual cramps for the past couple of months, which is new for me. I am 42 years old and was wondering if this could be perimenopause or fibroids.