What Causes Vaginal Itching And Burning Feeling In Bladder After Urination?

I have a burning feeling in my bladder following urination. After this, there is an itching type feeling inside the vagina that is slightly painful. This has been happening on and off for a number of weeks, and nothing seems to bring it on (eg this morning i woke up feeling like this). It normally lasts a few hours to a day or two, but I drink cranberry juice which I think stops it. Is it some sort of bladder infection? I've had cystitis before and don't think it's that.