Pain in lower pelvic on left side for months.

Kemba

So I have been having a discomfort in my lower left side it’s literally on top of my vagina. I’ve had ct, ultrasounds, transvaginal ultrasound, and no one can see anything. All I know is I have an anteflexed uterus but I doubt that is what’s causing the pain. On top of that whatever it is it causes my lower back to hurt. These pass couple of days are the worst I have and appt on in 5 and obgyn appt on Jan 19. I don’t know what this can be and I’m very worried it something serious. Does anyone know what could it be if it hasn’t been picked up by X-rays??? I haven’t had any weird bleeding or anything coming out of my vagina.