You may have swollen membranes that are blocking the opening of the eustachian tube. Decongestant nasal sprays, oral decongestants, such as sudefed should allow your eustachian tube to open up. Also apply a warm moist compress to the effected ear as well.
If there is no change to the ear by tomorrow after doing the above for today, then you should be seen to make sure there is no blockage of wax in the area.
Hope this helps, If you need anything else please feel free to ask. If you found this helpful don’t forget to click the *