Peeing every hour

Ive been peeing once every hour not sure why and no matter how much i pee i still feel full and like i still have to pee i never have relief...im still cramping and my period ended 2 weeks ago and having lower back pain that raps around my waist im constantly feeling full and cant have any pressure on my stomach or it hurts... can anyone help me im 17 and cant talk to anyone else about this and i dont believe its a kidney infection because it dosnt hurt to pee