Brief Answer:
Might be eustachian tube blockade

Detailed Answer:
Hi
Welcome.
I have gone through your query and information provided by you is very little.
I would like to know bit more information like,

1. Since when you are facing this problem
2. Do you have history of sinusitis
3. Are you suffering from cold, sore throat?
4. Is there any problem with hearing?
5 is there any discharge from the affected ear?

Presently based on the information I feel you might be suffering from eustachian tube blockade, may be secondary to URTI (sinusitis)

I would suggest you to see ENT specialist. Until you see the doctor, I suggest the following measures to see if you get better.

1. Avoid chilled food like ice cream, and also citrus containing fruits and juices
2. Steam inhalation with few drops of eucalyptus oil in it three to four time a day.
3. Salt warm water gargaling three to four times a day.
4. Take plenty of fluids especially warm water.
5. Nasal decongestant like octrivin will be beneficial.
6. Do valsalva manovere exercises ( watch youtube for procedure).
7. Chewing gum can be tried and yawning will be helpful.

Try this measures, you should see improvement.
Hope this helps.
Take care

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