when to call it acute pain....?

sudden onset of pain in any quadrant of abdomen without prior symptoms of pain called acute abdominal pain

is it an emergency?

usually colicky ( twisting) abdominal pain without accompanying nausea, vomiting, diarrhoea or fever subsides with simple medications

when to call a specialist doctor?

when acute pain associated with above symptoms, not subsides after medication ...it is a warning sign... you should go to hospital.

first line investigations.....

X ray abdomen, USG abdomen and blood investigations should be done to clinch diagnosis.