<s>[INST] I ve been experiencing back and abdominal pain, nausea and vomiting and a slight fever. I have a history of kidney stones so I thought maybe one was stuck, but I went to my urologist today and he couldn t see anything on an xray. He told me to have a CT scan and come back in 2 weeks. Meanwhile, I m still in pain,, still vomiting and still nauseous. Any ideas would be appreciated. [/INST] Hi, Thanks for writing in. Stones are deposition of calcium and other minerals in the kidneys and urinary tract. A stone might cause obstruction to the passage of urine and lead to obstruction. This obstruction of urine might lead to sedimentation and stagnation of urine in the system. When there is pooling of urine and obstruction then there is bacterial proliferation in the urine generated. This might be due to bacteria ascending the urinary tract through the urinary bladder and then involve the ureter and kidneys. Once it reaches the kidneys then it causes infection and bacterial growth. This leads to release of toxins and symptoms of pyelonephritis including nausea, fever and pain abdomen. In severe cases there is gas formation by the bacteria leading to a serious infection called emohysematous pyelonephritis in kidneys. Please do not worry. </s>