What Causes Frequent Cysts And Pain In Left Ovary?

I have had cysts on my ovaries in the past and always on the left side. both times were checked and pain was gone in a few days. Im 55 now and had the same pain on lower left side again. I usually take the motrin a few days like I just did and pain is gone now. I though since Im no longer having a period my ovaries would not do this??