I would definitely make an appointment with your vet. In fact, I'd probably run him to the emergency vet just to be safe. It's quite possible that he's having a very nasty allergic reaction. How is he doing now?
Has he shown any improvement since it started? What did your vet say? Did you see a neurologist? I would expect that a neurologist might have some ideas about whether or not it is temporary, especially if it has been confirmed to be the result of the Revolution Plus. If not, asking the vet/neurologist to consult with a vet university might be an option. Many due to their training/education, have a greater exposure to unusual cases.