Sometimes, the pain and stinging during urination is not connected to the urethra or vagina at all, but this reason is even more concerning. Another cause can be kidney infections, which are a more serious concern. If you experience pain during urination alongside blood in the urine and back pain, this may indicate a severe turn in a UTI progressing to a kidney infection. When a UTI spreads to the kidneys, the situation becomes more critical and if left untreated, kidney infections can lead to hospitalization, as they have the potential to infiltrate into your bloodstreams.