Anal cramps strung with back pain may be related to severe proctitis, kidney stones and pelvic effusion. 1. severe proctitis: when proctitis develops to a more serious stage, the rectal wall will have a large range of inflammation, so that the rectal wall is widely stimulated, thus causing anal distension string back pain. 2. Kidney stones: If the kidney stone patients have already appeared in the case of hematuria, indicating that the condition has involved the urinary organs, which may lead to the neighboring anal distension. And because the kidney is located in the lumbosacral region, when kidney stones cause pain in the kidney area, the lower back will also have a feeling of soreness. 3. Pelvic fluid: If the fluid in the pelvic cavity gives a certain pressure to the surrounding tissues, it can make the anus localized swelling sensation, and string of back pain and swelling. The situation of anal swelling and back pain, it is recommended that patients seek medical advice to identify the cause, follow the doctor’s instructions to give reasonable treatment, do not delay.