Brief Answer:
Post meal diarrhea

Detailed Answer:
Hi...
Welcome to Ask a doctor.

I hope that you are not on some medications such as antacids, antibiotics like amoxycilline plus clavalunate,cefuroxime etc or chemotherapy.They may cause diarrhoea.

Acute diarrhea after eating is a sudden onset of diarrhea which is due to stimulation of intestinal muscle movement with secretion of large amount of fluids and makes large intestine to empty the bowels. When there is an underlying cause such as an infection, food poisoning, or IBS,these contractions may be stronger ,painful than usual and come with a sense of urgency.

Commonest causes of Acute Diarrheas after meals is an infection.This is called Colitis.It can be bacterial infections such as Salmonella,E. coli,clostridium etc , a viral infection (commonly referred to as the "stomach flu") or a parasite infection such as Giardia (Giardiasis) or amoeba(amoebiasis).
This needs a stool examination and specific antibiotics or anti parasitic drugs(like anti amoebic drugs).

Second common cause is microscopic colitis which is a distinctly different illness than ulcerative colitis.Inflammation of the cells lining the intestines can only be seen when tissue is looked at under a microscope and can not be seen by naked eye.The cause of microscopic colitis is not well known. Its symptoms include persistent or intermittent episodes of watery diarrhea.

Third possibility is Irritable bowel syndrome with predominant diarrhea(IBS-D),which may also be a chronic cause.There are two forms of IBD— Crohn's disease and ulcerative colitis and both can cause the symptoms of diarrhea after eating.The diarrhea of IBD may have blood and mucus in the stools and may cause ulcerations in large intestines.This needs and endoscopy and histopathological examination for concrete confirmation.

Stay well hydrated as you need to replace the fluids and electrolytes which are not being absorbed and lost in stools
Don't use strong anti diarrheal drugs like Imodium as they may cause gastroparesis and distention.
Take small frequent meals instead of large 3 meals.Avoid fatty and greasy meals.Have more of fiber.De stress yourself as overthinking and anxiety augments the symptoms.Do meditate and be physically active.

Hope that I have answered your query.If you have any doubts,please l;et me know.
Stay healthy and stay blessed.
Regards

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