Hi,the cause of your listening ringing sound in the ear after middle ear infection might be collection of fluid in the middle ear after middle ear infection or Eustachian tube blockage(a tube which connects middle ear with the nose and is responsible for equalization of middle ear pressure with the outside atmospheric pressure). Generally, Hifenac or anti-allergic medicine does not cause ringing in ear. You might get relief by taking Anti-histaminic(like Cetrizine),Nasal Decongestants (like Otrivin nasal drops),tablet Betahistine(Vertin) and a Mucolytic. Also do steam inhalation.Avoid cold food.Avoid listening to loud sounds as they can aggravate your problem. Avoid giving much importance to the ringing sounds. If the sound is troubling to you,then listening to White Noise Music(available on you tube) might give you relief as White noise has a masking effect on the ringing sounds that you hear. You might get improvement by doing Brahmri pranayam,if you are aware of how to do pranayam. Hope this answers your question.Take care.