A few months ago, I had sharp shooting pains in my lower back (right side) on & off for around an hour followed by hours of a dull ache and nausea. Went to the doctors and they did a dip test in a urine sample- doctors diagnosed kidney infection and gave me antibiotics. Two weeks later and after three types of antibiotics, I was back to "normal"...or as normal as I can be anyway! 
10 days ago, it started again...I went to the doctors, they did another dip test and said there was protein and nitrates present which indicated infection and prescribed yet more antibiotics and sent sample off for further tests. Results came back today showing there was no bacteria (so it couldn't be an infection) and traces of blood...doctor said that tests need to be re-done (but have to wait until my period finishes and I am not very patient!) and if the results come back the same, I would have to go for more tests and scans (didn't confirm what but I'm assuming kidneys?)
Anybody else had symptoms like this and what was the diagnosis?