The pain may be due to an ulcer in the stomach or gastritis.
For both conditions the diagnostic procedure isnot ultrasound
that is endoscopy.
But before endoscopy you should avoid chillies and fried food and take soft diet
for few days that will resolve your problem and take Proton pump
Inhibitor to reduce gastric acid
secretion to damage the stomach walls I hope you will be fine.
I hope I am succesful in solving your query if you have more you can ask me.
Dr. Azhar Sattar