Cat weird symptoms, vets don’t know

These episodes started 12 days ago. At first it was happening once a night. On the 3rd night we started him on cortisone and antibiotic shots , and an iv treatment all day that had electrloytes and b-complex.

Then the symptoms stopped for 4 days.

Then they started again, happening twice a day. Even though I continued to give him cortisone and antibiotic pills at home.

The episodes usually last 2-3 minutes, and he gets lethargic for 10-15 min after that. Wobbles a bit like he’s drunk. No foaming or drooling around the mouth.

His blood work and x ray are normal, but ct scan shows inflammation in the brain.

I’ve seen 4 different vets in the past 12 days, each one has their own opinion. And they all say to continue giving him the prednisolone and clindamycin.

But he’s getting worse, not better. Anybody have any clue? What else should we test? What can it be?