How many famines can you do at a time?
As many as you want.
Famines in themselves do not cause disease; they cause malnutrition, which is a preventable condition that can be considered as a disease. There are other diseases that are common in areas where there are famines and most of these have to do with sanitation. The leading killer in the world is cholera which is from drinking unsafe water.
Since you are not giving a date, it is hard to say. There were many famines in the history of Europe, and black bread might have been one of the things in short supply. Black bread has been available in Europe since prehistoric times, and I doubt there was ever a time in history when there was none at all.