You have likely "Otitis Externa". This simply means you probably have an infection of the outer ear and canal. Very common.
Sometimes called "swimmers ear" in those who have been swimming.
You will need antibiotic drops and pain control. You need a prescription to get what you need.
If you are diabetic, be particularly careful and get seen right away.
Also, if you notice pimples or blisters on your ear, this may mean it is shingles and the medication used is different.
Hope this helps guide you.