What Causes The Menstruation Cycle Shorter At The Age Of 49?

Hi, I am 49 years old, not on the contraceptive pill. but I have been having frequent periods. The cycle was getting shorter. I had a period on the 124th March then 19th April then 3rd May the 3rd June and now again 19th June. The periods last about 6 to 7 days. I s this normally for my age or is there something wrong?