The painful spasm at the anal canal: 1, because of the recent eating of unclean food, resulting in the imbalance of the normal intestinal flora in the body, the infection in the intestinal tract constantly eroding the intestinal canal, the painful spasm of the rectum and anal canal. 2, because of hemorrhoids in the anal area, these hemorrhoids attached to the rectum inside the anal canal, after stimulation will constantly pull the skin mucosa around the anus, causing this phenomenon. 3, proctitis The reason for this is that when the body takes in less water it causes dry stool, and when the dry stool is passing through the intestines, it will stimulate inflammation and polyps causing pain. 4, because of the usual lack of attention to the hygiene of the anal opening, resulting in bacteria and viruses entering the rectum through the intestines and multiplying in the intestines, thus constantly stimulating the intestinal canal causing pain.