Please go see a doctor.
UTI normally comes with pain while peeing with the frequent need to go to toilet symptoms. And UTI can travel up to your bladder and kidney if not taken care of. When the infection of UTI travels up to the bladder or kidney, we'll feel pain in the lower part of our back.

But it could be a normal back pain also. So you should really go see a doctor.

There's something call Ural which can be bought at pharmacies for about RM10-15 to cure mild UTI. Dissolve in water and drink 3 times a day. Also drink lots of water to flush out the UTI.
Prevention can be done by taken cranberries (or can opt for cranberry pills since fresh cranberries are quite hard to get in msia) and also drinking lots of water. Don't try to hold in your urine for long time. Wash up and pee after sexual intercourse.

Omg! That's very bad! Have to drink minimum 7-8 glass la!

It's still better if you go see a doctor. Because UTI normally treated by antibiotics if it's not in the mild stage. If your urine have blood and still pain then please go see doctor straight away. Don't delay UTI, it'll only get worst. Also, I'm not sure whether you can still consume Ural if you already don't have the symptoms. So yea, like what frostworld say, check with a pharmacist if you decided to get some.