The first consideration is that it may be caused by intestinal spasm. When walking, the small intestine may have spasmodic pain, which is manifested as a burst of pain or even vague pain, and the pain can generally be relieved by itself when resting, which is a normal phenomenon. If there is often hidden pain in the left lower abdomen, it is necessary to go to the hospital for examination, because it may be a colon tumor. In case of colon tumor, there is no symptom in the early stage, but when the tumor progresses further, it can be manifested as vague pain in the left lower abdomen, which may be accompanied by some symptoms of digestive tract, such as increased frequency of stool, thinning of stool, even thin stool, and bloody stool. If necessary, colonoscopy can be done because it is more visual and can detect lesions inside the colon or perform abdominal and pelvic CT to find out whether there is a mass in the abdominal cavity. If colon tumor or sigmoid colon tumor is considered, radical surgery is recommended.