I have constant pain by my kidney and also have both white, & red blood cells in urine. What could be the cause?

#1= infection, #2 =? Obviously you've had a urinalysis. The next step would to go over this with your M.D. The question is what caused the infection, and is it secondary to other problems such as kidney stones, some other inflammatory process (of which there are many). Autoimmune diseases, reactions to medications are all possible.