what could have been the reason for the foul odor from my anus

I recently noticed a foul odor from my rectum after showering. I went online to try and remendy the odor because clearly soaps werent working, I even tried using rubbing alcohol. The most common suggestion I found was that the odor may be caused by anal fistula, i did however find one useful and AFFECTIVE suggestion which was to lather my rectum with soap and push finger slightly in my rectum several times to clean right inside the opening, not only did the odor go away my anus instantly puckered up and tightened!! Although I am very pleased to have found the solution Id like to know what the problem was in case there may be more serious issues involved than odor which could be a symptom to a bigger issue