There are several reasons that cause a tense rectum. The first is that the rectum is filled with fecal matter that is relatively dry and hard and is very difficult to defecate. This is directly caused by eating too much garlic. To resolve the “problem”, eat less garlic, drink much more hot tea, and eat much less red meat. Go for fish or chicken or go completely vegetarian.
To resolve rectum tenseness, go find some Senna leaf (folium sennae). Make some tea and sit and wait to run to the bathroom several times.