What Causes Ringing In Ears Along With Muffled Hearing?

For the past six months, several times a month, I have been having a loud ringing in one ear, followed by hearing loss and my ear feeling plugged up for about a week. My ENT doc put me on Propranolol for migraines. It hasn't got rid of it but it has lessened the number of episodes. Now lately, I'm getting a brief foul smell and then a dizzy head rush that lasts for only a few seconds. All my symptoms are on the left side. What is going on?