Can you tell me if a doctor says there might be some bacteria in the stomach how serious is this ?

H. pylori...: The stomach is a highly acidic place, and the high acid levels prevent many bacteria from being able to live there. Some bacteria (like helicobacter pylori) are able to live in / infect the stomach and cause inflammation of the stomach lining which can lead to upset stomach and other symptoms. This type of infection is treated by combination of antibiotics and peptobismol. Hope that this helps.