I had it explained to me this way by an OB/GYN:
As you're getting lower on your egg supply, your body actually starts to cut into your ovaries for available eggs. That causes pain around mid month, and often some spotting. The timing of the periods sounds like perimenopause.

I have found this thread to be interesting. Recently, I've experienced intense ovarian pain--so bad that it woke me up twice in one night! I also have 2 fibroids so sometimes when I have periods, they are quite heavy with large clots but no cramps. However, the ovarian pain was only recent. I went to the ob/gyn and she ordered an ultrasound. Since being diagnosed with fibroids, I've had 3 ultrasounds. The first one the technician and radiologists couldn't find my ovaries. They looked externally and trans-vaginally. The second time the technician had no problems finding my ovaries. Now, the third time around neither the radiologist or technician could find my ovaries. This concerns me but apparently, my doctor isn't concerned at all. I'm now left deciding whether or not to see the doctor again and insist that they find a way to see my ovaries or let it go. I haven't had any ovarian pain in a month or so. Thank you for posting a possible explanation for ovarian pain. I was hoping that I was nearing the end of my periods since I went 6 months without one but then they came back with a vengance--the ovarian pain and very heavy period. Right now, I'm more than ready to have an end to periods!