There are three conditions to consider when you have anal pain after diarrhea, the first being hemorrhoids caused by diarrhea. Hemorrhoids are not only caused by dry stools, but repeated diarrhea can also cause perianal hemorrhoids to become edematous, or cause pain, or even cause thrombosed external hemorrhoids. The second condition, anal fissures, can be caused by repeated bowel movements and diarrhea, which can also cause the perianal mucosa to break down and form anal fissures. But most often there will be blood in the stool. In the third case, anal sinusitis, in addition to anal pain, sometimes there is also a burning sensation in the anus or an uncomfortable swelling in the anus. The diagnosis of the above three cases is also relatively simple, and anoscopy can basically make a clear diagnosis. The first treatment is to treat the diarrhea with oral antibiotics, such as ofloxacin or safranin. If the diarrhea is heavy, you can also take oral montelukast. Next, you can treat the symptoms, such as the use of hemorrhoid suppositories anal, such as Ma Yinglong hemorrhoid suppositories or Tai Ning suppositories anal.