Hi.
Thanks for your query.
Noted the history and understood your concerns.
Uncontrolled burping, white foam, sometimes yellowish fluid, burning sensation in chest for 2 months suggest that there is a condition called GERD that is gastro-esophageal reflux disease.
Recent development of much gas and yellowish brown feces indicate
enteritis .
Hence I would advise you the following:
Upper GI
Endoscopy to know the condition of
esophagus, stomach and 1st part of duodenum.
Tests of blood and stool.
Get started with the PPI like
Omeprazole.
Domperidone to avoid reflux.
Antibiotic if there is an evidence of intestinal infection.
Probiotics and activated charcoal.
Boiled cooled water and fresh foods only that suits you.
Soft bland diet. Small frequent meals.
Watch for the progress and see if you need to see the Gastroenterologist for further evaluation and management.