Uti or kidney infection?

I’ve being having a pain on side/back at first it would only be when I urinate but now it hurts when I’m just relaxing , the pain on my side stings has anyone had this ? I want to go to the doctor but my doctor doesn’t have any available appointments till next month :( I’m thinking of going to the er to be sure . I’ve had uti’s in the past but I don’t remember having this pain.