Welcome to health care magic.
Thanks for your query.
By ultrasound Gastritis
can not be diagnosed.
A kidney stone may cause back pain
when its passing through the urinary passage.
You are drinking sufficient water.
If you have burning sensation in chest or pain in upper abdomen or belching etc then you can take antacids for few days.
Get your blood pressure checked.
Back pain may be due to sprain or local muscle inflammation
Make your posture right while sitting and sleeping.