What Is The Condition Causing My Tinnitus, Muffled Hearing, And Dizziness, And How Can I Alleviate The Symptoms?

I have tinnitus and muffled hearing/ hearing loss in my left ear, also a dull eardrum but no infection. I have recently started experiencing dizziness and vertigo but no nausea. My GP has referred me for an MRI scan and has said there s a nasal spray I can use to help. This started after I had flu a few years ago. She was concerned that this one sided condition could cause further issues. What is this condition called, what else can I do to alleviate the symptoms how can I be further affected?