Is There a Definitive Test for a Fistula Between the Middle and Inner Ear?

As my recent 7 week incredible tinnitus spike and hearing change was caused by an occasion event... I'm wondering if I could have a fistula between the middle and inner ear.

Does anyone know what would be the test for this? Would a CT scan show it?

My voice immediately sounded weaker after the event.. muffled. And now have bad hyperacusis.

 

I think it depends on the size of the fistula and the resolution of the CT machine.

 

What was the event?
If it is not, unintentionally, an indiscreet question, of course.

After my tinnitus onset I remember that straining on the toilet may times triggered an "eeeeeeeeeeeee". Very scary!
Later I read somewhere that when you have a fistula stool softeners are recommended, so straining is avoided, so healing, the closing of the fistula, has best conditions to happen.

I have also old tinnitus, 10 years.
It is worse now.
I do not know the exact cause of my tinnitus, many things happened. Now I am thinking one of the following three: fistula, endolymphatic hydrops and ETD, eustachian tubes dysfunction, and after 10 years of tinnitus (now much worse) I still do not know the answer to that question...
And prior to tinnitus onset I had terrible acoustic trauma...

@MJ Burton