Since my teens, I had painful periods.
About 6-7 years ago, I suddenly got an awful pain in the right illiac fossa region (about appendix area).
Thinking it was my appendix, I went to the doctor and was told there was nothing wrong.
The next month, it happened again.
Then, the following month it occurred in my left illiac fossa.
Then it dawned on me. I was ovulating.
Since the first time it happened, my periods are now only mildly uncomfortable (no cramping pains, no more time off work cuddling a hot water bottle) and it doesn't matter how irregular they are, I know the 5-7 days after the pain stops, my period starts.
They even stopped for nearly 6 months. I thought it was great. 
Then they started again. Same pattern. Ovulation pain which affects peeing and pooing and then my period a week later.
I'm 49. I would really, really like to stop the whole tampon buying faff too.