Cramps and back pain...

Since Thursday I've been having cramps in my side and the occasional sharp pain in my lower back. Its very brief and will only hurt a few seconds. I thought maybe I needed more water. But that's all I've been drinking. Those symptoms wouldn't have anything to do with signs of early pregnancy would it? Could it be from sex? Idk.... I thought maybe a kidney infection or kidney stones. But the pain isn't that intense. Its a dull pain that comes and goes. Any ideas as to what could be causing it? I don't think i'm pregnant yet.... So idk...