Severe back pain after fever may be caused by colds, kidney stones, urinary tract infections, etc., and you should consult a doctor in time to find out the cause. 1. Cold: When you have a cold and fever, some of you will have symptoms of severe poisoning, such as chills, diarrhea, and general muscle and joint aches and pains. Cold and fever sometimes trigger the immune response, resulting in kidney damage, such as congestion of the kidneys in the acute stage, can also cause significant back pain. 2. Kidney stones: Kidney stones themselves do not cause fever, but an embedded kidney stone may become infected and cause an increase in body temperature. Kidney stones are transferred to the ureter, causing irritation and blockage of the ureter, resulting in significant back pain. 3. Urinary system infection: when the patient has a urinary system infection there will be obvious fever, chills and so on. The aggravation of urinary system infection, the formation of perirenal infection, renal abscess, etc., will cause more serious symptoms of back pain. There may be other reasons for back pain after fever, it is recommended that the patient consult a doctor in a timely manner to clarify the cause of the disease, follow the doctor’s instructions to actively cooperate with the doctor’s treatment, do not self-medication, so as not to delay the condition.