Hello

Primary advices to deal with stomach pain :
1. to relieve pain , you may use an OTC medications such as Bismuth Subsalicylate
2. lay down on your left side 
3. have a healthy diet , avoid over-feeding 
4. avoid smoking 
5. make sure you are not taking any medication that cause stomacheache as a side effect 
What is the treatment of stomach pain ( if presisted )?
1. consult an internal medicine doctor to do the needed medical examinations and determine the treatment pathway 
2. in case of H.pylori infection , doctor will prescribe antibiotics such as - clarithromycin, metronidazole , amoxicillin
3. doctor may also prescribe  nadine to relieve nausea and vomiting 
4. to reduce stomach acidity , you may used PPI medication such as omeprazole and anti acid medications such as ranitidine
5. in severe cases such as internal bleeding , patient may go under surgery 
What is the possible cuase of your medical condition ?
 - the expected cause in your case is unhealthy diet and unsuitble food , but other causes may include :
1. infection
2. medication side effects
3. ulcer