Generally there would be some UTI symptoms present in there is kidney involvement, but again that is just a generalization. As Linda in NJ mentioned stones are always a possibility, although I have never experienced them with my daughter so I am unsure the symptoms of them.
Sometimes the blood in urine is trace amounts and not noticeable. With the decreased urine output there is something definitely going on. There are some over the counter medications you can get...not sure if they have the same name where you live...but AZO works well...it is an analgesic so it decreases pain and relaxes the bladder. Also cranberry juice is good...not the cocktail variety...but pure cranberry juice, or capsules.
I hope you get answers soon...even though I don't suffer from any type of UTI's (knock on wood), I understand the pain/frustration you must be feeling...my daughter has suffered for a few years with them.
Good Luck again!!
Angela