Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. That varies a lot. Typically, if symptoms occur immediately after ingestion, it suggests a problem in the stomach, e.g. gastritis, peptic ulcer. If it happens after ½ hour to a few hours, it is more likely caused by malabsorptive states in the small intestine, but it can also be IBS. Hope I have answered your query. Let me know if I can assist you further.