What Causes Frequent Urination, Abdominal Pain And Inter Menstrual Vaginal Bleeding?

I have had tissue loss during my period for the last 4 months (I have had a miscarriage before and the tissue loss is close to this during each period but am not pregnant as I had had ultrasounds and bloodwork at each period as well). I am now urinating frequently, having abdominal pain for the last 3 weeks and on and off bleeding that is not during my period. I have had an ultrasound checking my uterus and ovary and found nothing. The pain on my right side (feels like ovary pain) is getting worse. At this point what do I do because nothing was found on the ultrasound even though I know something is not right with the bleeding, the tissue loss and now the severe abdominal pain and frequent urination.