What Causes Pelvic And Abdominal Pain?

Hi, I've been suffering with pelvic / abdominal pain for a couple of months along with backache and intermittent diarrhoea. I had an ultrasound in September last year which came back clear (a small cyst was detected on one ovary). I have also had a colonoscopy which was clear. I am due to have another ultrasound in a week but am really scared that I have ovarian cancer.