What do you think is going on with my cat?

I think he is suffering from neurological problems. I think this because of the dilating pupils- when pupils are dilated and there is no damage to the eyes it shows that there is something wrong in the brain. Whether it is illness or brain damage, I can't say. You'll just have to wait for the vet. But it is definitely something neurological. Maybe he is suffering from a small stroke or seisure.