The gastritis that was diagnosed can lead to your symptoms. The upper endoscopy has already been done - which is a pretty comprehensive test. You may also want to consider blood tests to look for H Pylori - which is sometimes associated with gastritis. Antibiotic therapy to treat this would help with the symptoms.
As for IBS, this can be considered if other causes have been ruled out. Increasing the fiber in the diet is the normal initial treatment. If the symptoms continue, antidepressant therapy, antibiotics (like Rifaximin) and antispasmodic agents can all be tried.
These options should be discussed with your personal physician, or in conjunction with a gastroenterologist.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
kevinmd_
God bless and I hope you feel better soon,
KentuckyBeMommaw/Christina