Hello,
Welcome to HCM.
Causes of gastritis are helicobactor pylori infection,oily and spicy diet,or it could be drug induced.
Gall bladder pain is mostly felt over upper right side of abdomen rather than over stomach region.
Bur you can go for routine blood count,ESR,urinalysis with ultrasound abdomen with upper GI endoscopy to rule out other gastric or liver pathology from which ultrasound and endoscopy you have already done and the reports are indicative of
acute gastritis and liver cyst.
You may require h2 blockers like ranitidine or
proton pump inhibitors likepantoprazole,
rabeprazole etc with cryoprotective drugs like sucralfate,misoprostol for gastric symptoms.
It underlying cause is H pylori then you will require triple drug regimen means two antibiotics and PPI.
For liver cyst,you will require antibiotics (preferably
levofloxacin) for at least 10 to 15 days with doctor's prescription.
So,better to consult your physician or gastroenterologist for further treatment who will know about it.
Regards,