What you are doing is great, I also suggest that you see a doctor and have a complete urinalysis and blood panel run, this will rule out any infections and such.
If you have a urinary track infection, you should keep drinking alot of cranberry juice, but if it wont go away go to the doctors to get a pill for it if you let it pro long then it will get worse, or it could be gull stones.
Your doing right by drinking lots of water and cranberry juice. Find a urologist and go to them. I had a uninary track infection and got treated for it and came down with sepsis (blood poisining).
It could be a UTI, you should see your doctor and get a urine test.