Serious Uterus Pain

My husband and I have been ttc baby #1 for almost a year now. 8 months ago I had what the doctors think was a cyst rupture. I have gone back for checkups since then and no other cysts have been found and I'm always told that I have a "beautiful uterus", but ever since then every month around the time I ovulate and when I start my period I have intense uterus pain. The pain is sudden, sharp, and sometimes moves to my rectum. TMI but my periods ever since then are light and the last few days the blood is always super dark, which I never had before that. 
Has anyone else experienced this? The doctors aren't finding anything and I'm worried it's prohibiting us from conceiving.