Sorry to read you are going through this. Exhaustion can wreak havoc on the system. Have you seen a doctor about this, perhaps a neurologist? The auditory things you are hearing, can have a physical explanation, located somewhere in your brain. And with something like that, in your medical files, it will be much easier to prove you aren't lying to your employer.
Keep going in! As hard as it is, that's the only way to grieve, as a union employee. Glad you have a rep behind you!!

Hang in there, and keep us posted.