Brief Answer:
depleted gut flora

Detailed Answer:
Hello and thank you for choosing HealthcareMagic for your query,

I've gone through all your details and appreciate your concern.

Most likely, the problem you are having is called Dyspepsia.

Dyspepsia, in layman's language is known as indigestion. It is a term that describes discomfort or pain in the upper abdomen. However, it's not a disease in itself. Dyspepsia is a group of symptoms which often include bloating, nausea loose stool etc.

As the onset in your case is acute(one day history) Most likely cause of indigestion is due to either overeating or taking over oily or fatty food.
Take a proton pump inhibitor like Esomeprazole 40 mg twice daily along with a prokinetic drug (eg.Domperidone) for 3 days. This will provide you symptomatic relief from symptoms
of dyspepsia (you may need to obtain prescription for this from your local physician).

Antacid like Pepto bismol can be taken for few days along with it.
Any over counter probiotic should be taken for few days to provide relief in symptoms of indigestion.Start taking a probiotic -Long term chemotherapy causes depletion in level of good bacterias.The mucosal surface of the human gastrointestinal (GI) tract is colonized by 1013-14 bacteria of 400 different species and subspecies. Gastrointestinal microflora is catagorized into two types, autochthonous flora (indigenous flora) and allochthonous flora (transient flora). Autochthonous microorganisms colonize particular habitats, i.e., physical spaces in the GI tract, whereas allochthonous microorganisms cannot colonize particular habitats except under abnormal conditions.Most pathogens are allochthonous microorganisms; nevertheless, some pathogens can be autochthonous to the ecosystem and normally live in harmony with the host, except when the system is disturbed. Toxins released by medication destroys this flora and cause problem like loose stools bloating belching etc.

Bloating and acid can be caused by any kind of food. In most of the cases, it's fatty foods which cause these symptoms. Any food whether it's fat or protein or complex carbohydrate when can not be properly digested, releases large amount of gases like hydrogen, methane, carbon dioxide which causes burping.
Hope I've answered your query.
Feel free to ask any follow up questions.

To be in safe side go for ultrasound abdomen test to rule out chances of bowel obstruction.

Regards!

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