It could be an AN. It could be a gazillion other things as well. I would think an MRI would be a good way to help narrow things down. Maybe he should get another ENT?
99% of the time tinnitus is my only symptom. However, I have had bad dizzy/vomiting attacks and mild hearing loss. I didn't notice the hearing loss and the dizzy/vomiting was written off as benign vertigo by the ER docs since they only lasted a few hours and were years apart. So, in a way, tinnitus is my only symptom.
For some reason, some Dr are quick to get CT scans. But, CT scans only give limited info and involve a fair amount of radiation. Ultimately and MRI is needed to figure things out and I am not sure why they don't just go to the MRI earlier. Maybe insurance companies and cost get involved? If I had tinnitus that bad and no explanation for it, I'd want an MRI for sure.