I would like to ask a few questions as follows.
Always provide your age and sex when you ask a question as it provides a lot of clues to the diagnosis.
Do you have any discharge from your ears.
Do you have any discharge from your nose.
Do you have any tenderness on your face.
Does the pain increase on bending your head forwards.
Do you have any recent history of fever
Do you have any harness of hearing.
Depending on your answers you could have the following condition.
Probable infection of middle ear.
As far as gastritis
is concerned, this can be addressed by anti gastritis medications.
I suggest you get your throat, ear and sinuses
examined by a doctor. Also an xray of the sinuses could provide some information.
The doctor on examination can decide if your condition can be managed medically with medicines or needs surgical intervention.