Chronic or prolonged periods of diarrhea is a factor associated with hemorrhoidal developement. Tenemus, associated with diarrhea, is thought to severely stress the vascular system within the lower GI tract, causing internal pressure on weakened vascular structures that make up the hemorrhoidal tissue. This can cause a rapid deterioration in the damage, resulting in a quick progression from a simple stage I to a stage III or IV external hemorrhoid(s). Clearly, the elimination of the diarrhea is critical, both short and long term, to the improvement of internal hemorrhoids. It's not the diarrhea itself, but the straining which is the culprit.
When the tissue is in a crisis state, it will stay inflamed for a period, until whatever is causing the increased irritation is reduced or removed. Then, slowly, with the application of conservative measures (such as warm and cold sitz baths), the tissue will recover and the swelling will reduce. Pain, associated with internal hemorrhoids, can result from pain associated with a stretching of the mucosa (the surface tissue lining the rectum and anal canal). It can also result from the internal hemorrhoid expanding below the dentate line in the anal canal. The dentate line is a border above which pain-receptive nerve cells differ from those below it. Internal hemorrhoids which have expanded into this lower area encounter pain-receptive nerves, which can result in considerable pain, especially if the tissue remains swollen and the veins severely varicosed.
Over-the-counter medications such as Preparation-H, can be applied to reduce pain and swelling. These are designed to work within the first half-inch of the anal canal. Deeper application is not recommended as the compounds get absorbed at different rates with internal tissues. These will not cure the situation, but only provide temporary relief. Long term, you need to take proactive measures to reduce any contributory factors that might be causing or worsening the situation. There are also long term home based remedies available to assist the body in fully repairing the damaged tissue. In advanced cases, surgical intervention might be warranted. It is important to understand, however, that even with surgical intervention, without altering those factors that led to the hemorrhoids forming, they can return.