Correct English is "i have a pain in my ear" or more proper "I have an ear ache
As a native English speaker, the most natural way for me to say this is to say "I have an earache."
This is interesting. Hopefully someone can come by and tell us what the infinitive is. Searching a bit, I find the verb "боліти", but its third person singular conjugation is "боліє". However, Ukrainian Wiktionary also has articles for seemingly fixed expressions involving "болить," e.g. "сердце болить".
Well, its different words. Ear "болить" (have pain in ear). Person can "боліть", but it is a bad language ("суржик"). Human can "боліти" (be ill). Its better. But right word is "хворіти". Keep well! ;)