Dear WWB - I don't know if this will be of any reassurance to you: I was investigated for blood in my urine when I was pg with DD (now 6). Had ultrasound on kidneys (had a little look at baby too, v.sweet), then after she was born, xrays on kidneys, then I can't remember what it was called but a tiny little camera put up into my bladder (endoscopy?) via the urethra. Before that procedure they sent me a leaflet explaining about the procedure and warning in a gentle way to expect a little discomfort. But I felt nothing at all! About 100% less discomfort than a routine smear test, for which they DO NOT send you a little leaflet telling you to expect discomfort, do they?
The upshot was - nothing detected. As far as I know, I still have the condition. Blood in my urine was picked up when I was pg for second time. But no further investigations were deemed necessary. I only offer this by way of comfort that sometimes these things just happen and do not mean some serious underlying problem.
Poor you, poor dd, hope you get to the root of it quickly.