kidney infection causing pain and exhaustion ?

I would like to know if the symptoms I am having are related to a kidney or a urine infection. My doctor told me that I had to repeat a urine culture because he was not comfortable with the results. My second test came back indicating there was bacteria present. Since I was not complaining of pain during urination or any other symptoms that relate to urinary tract infection, he told me to take cranberry pills and drink lots of water for two weeks and repeat another urine culture. Now I am worried because I did not tell him that I was having an increase in aches and pain along with burning sensations in my back - kidney area. The last three days I have been extremely exhausted, as if I did not get enough sleep (I sleep well, 6-7 hours a night). The reason why I did not mention these symtoms was that I had them for a while +10 years, and came up negative for kidney problems. The exhaustion is my main concern and the pain in my kidney area is progressing. I don't want my doctor to think I am a hypochondriac so I kept my other ailments to myself and focused more on the pain I was having in my breast (I have new pain and swelling in one breast), which was my main reason for seeing him. My cholesterol/hdl ratio was high (4.9 - fasting), hdl was low (36), cholesterol (176), which is high for me since it was 143 not to long ago, and eGFR>60. At first I thought maybe I was pregnant due to the sudden exhaustion and increase pain in hip and back area but now I am not so sure. Is this something I should look more into? I heard that if a kidney infection is left untreated, it could lead to kidney failure? Is this true? Thanks.