40 years old. Always had the mild cramping with periods. However, over the last year in the first few days of my period starting I'll have an agonising sharp pain in the side of my abdomen that radiates through to my back. I assume it's where my ovary is? It only lasts 30 seconds or so and comes and goes. Leaving a dull ache afterwards. But the pain is enough to have me doubled over and clutching my stomach. Any ideas what this is?