It is twitching and very sensitive to sound he is also very off balance

Taking him to the vet would be the logical thing to do.

No-one on the internet can diagnose your cat.
Shaking often means pain.
Mouth opening and closing could be neurological or to do with his lungs or airway.
Sensitive to sound and off balance could be an ear infection.

They are all only guesses, you need to see a vet.