It is important to know the cause of your diarrhea, as it could be caused from a virus, food poisoning or medical condition.
The erceflora you were prescribed....did your doctor perform any tests to determine the cause of your diarrhea? Did you take this as prescribed, with plenty of clear fluids (water, broth)? Since this medication was not effective, it is important to contact your doctor to let him/her know, and move to a different type of treatment (and receive a proper diagnosis first).
Have you tried the BRAT diet, instead of chicken and potatoes? This means eating: bananas, rice, applesauce, toast until your stomach feels better. Most cases of diarrhea should only last a day or two. If you are experiencing this for going on three weeks, it may be considered chronic diarrhea and seeing a doctor is necessary.
This is helpful information from the National Cancer Institute: diarrhea.