Hello, sivan,
Sudden onset of
abdominal pain with an urge to have a bowel movement
and the relief after the act is suggestive of some acute inflammatory
process . It quite possible that you might have eaten something that
was contaminated by bacteria. This is causing
gastroenteritis and you
may even have some slow bleeding from the stomach, Digested blood
comes out black in the stool. If you are not taking Iron supplements
or bismuth compounds, then bleeding in the stomach has to be considered.
Please see a doctor ASAP , so appropriate measures can be taken. In the
meantime , avoid
aspirin,
ibuprofen type of drugs and stay on bland diet.
If it is food
poisoning, it will clear quickly with time.
Sometimes, you may need an antibiotic therapy.
Wish you well.