Living with Overactive Bladder

For the past month or so, I have started to experience a problem with frequent urination. My bladder feels completely full and when I go it empties out. Within an hour or so, I have to go again. This continues throughout the day and into the night. I get up about 3 to 4 times during the night. I have seen my doctor and she took a urine sample for testing. It came back with (hidden blood) in the urine. So, she ordered an x-ray of the kidney, bladder area and an ultrasound for the kidneys. The x-ray returned with no problem, and another urinalysis showed no blood. I have not heard back regarding the sonogram. She wants me to have a scope and camera inserted into the urethra, but I do not want to have that done due to the horror stories I have heard. If nothing negative shows on the ultrasound, then I am wondering what the problem could be. It may be an age issue or post menopausal. I am 57 and finished menopause at 50 without any problems. Please give me some insight into what possibly could have brought this one so quickly. Since, I did have a back ache and the other syptoms that I mentioned above, she did prescribe me Avalox for the possible kidney infection.
Thank you so much