What could cause low fever, chills, lower back pain?

Many things: Many infectious problems can cause such symptoms. Most common would be a urinary tract infection or kidney stone. Often this will come with burning during urination. Ovarian cyst rupture or pelvic inflammatory disease can also cause these symptoms. Appendicitis and diverticulitis are in the mix, as well. If it worsens or persists check with your doctor!

Infection : You could have a bladder or kidney onfection. You should be seen by your doctor.