Lots of people have blood cells in their urine and a cause is never determined. Yes, it can be a symptom of bladder cancer, but usually it is not. Unfortunately, many doctors ignore this in women since they think it is "normal" for us. It would be a good idea to get a referral to a urologist for an evaluation, but do not be surprised (but pleased) if it is not found to be bladder cancer.
Symptoms of bladder cancer are variable, and do not usually include pain. While urinary blood cells do show up, I, for one, have never had any. I was diagnosed after a year of repeated "rip-roaring" UTI's with no bacteria found. Other people do not experience anything like this.
As I mentioned above, you should go to a urologist who can determine whether there is any sign of bladder cancer. IF it is present, remember that it can be successfully treated when found early (which is why you SHOULD see a urologist. But don't be surprised if the cause of your red blood cells is never found.
Sara Anne