need more details

For a change you accept that your knowledge of foods that trigger gas formation is inadequate. That's how in spite of avoiding all those foods which could trigger gas formation, you are still having severe gas and backache and pain chest. Please consult with a General Physician in your area. A physical examination and a few investigations are required. Now your Google knowledge is not good enough.

Use syrup gestid 2tsf thrice a day Tab pan d empty stomach in morning for 5 days If don't get relief then Can help you, kindly consult by giving history for proper diagnosis and further management

Consult on practo

You might be having gastritis. Need more details consult me online for proper evaluation and treatment

8months long symptoms, should be evaluated properly with blood investigations and examination. Meanwhile you can try some over the counter antacid medicine