This is a very common symptom. At your age, the most common cause is likely due to sensitive stomach which can produce symptoms like bloating, feeling fullness after meal and gastric pain. The cause of the sensitive stomach can be related to our diet, lifestyle and stress.
You need to monitor for features like weight loss, passing out black stool or pain waking you from sleep at night. If you have such symptoms, do consult doctor earlier.
Otherwise, try to avoid food which can irritate your stomach like spicy and oily food. Don't overeat. Try to have regular meal timing and adequate rest/ sleep. Avoid unnecessary medication especially painkiller. You can try to get antacid from pharmacy which can also help to relieve the symptoms.
I will suggest if it persists after doing all these measures, you should consult a gastroenterologist for evaluation of other causes like gastric ulcer or Helicobacter pylori infection in the stomach.
