I would go to the doctor asap most humans pee more than once daily! Unless you are not taking enough liquids and something else more serious can be going on . Hope you feel better and get that checked out immediately I wouldn't wait even admitting yourself into the hospital if you have to.
To give you a better answer we will need more information like, have you been ill? Have you had kidney issues now or in the past? Are you on medications? Do you exercise enough to sweat it out?
However, first I would say start drinking water,, the average woman needs 9 cups of beverage a day. If you exercise (play sports) drink more.
Your back hurting can come from dehydration or a kidney infection. If it continues see your doctor.