For several weeks I have been noticing minor discomfort when urinating; slight burning but not painful, and then I started passing cloudy and blood tinged urine. Next came the pain across the lower abdomen, and lower back, then pain around the kidneys. I went to a walk in clinic and they did a urinalysis as well as prescribed an antibiotic. They said that that they would culture the sample and get back to me today. Today they called and told me that my sample was "negative." How is this possible? I have been taking the antibiotic since Saturday but feel very ill, weak and tired more than my usual and have been sleeping a lot. No fever but definitely chills and nausea. Any ideas, anyone?