It only happens when i ovulate with the one ovary i have remaining and i am 70 years old.

One ovary at 70?: More information is needed to respond to this: it is not clear to what "It only happens..." refers, but it is extremely unusual for true ovulation to occur at age 70.

Doubtful: And 70 years old, you would not be ovulating.

Vaginal bleeding?: If you are getting periodic vaginal bleeding at age 70, it is urgent that you get a Gynecology evaluation.Abdominal cramps can occur from multiple things but if severe, deserve evaluation.