We found this chipmunk in our yard and somethings wrong with him?

There was this chipmunk in our yard with a nut in his mouth, his head ****** side ways and acting oddly. He was running in circles and seemed disorientated. I put gloves on and picked him up, yes he tried to avoid me. He spit the nut out... i had thought the nut was stuck in his mouth. So I put him down, he did not run away. His head is still ****** sideways as if he cannot move it and he was still running in circles... even running over my foot a few times. He went back and got the nut. I love animals and dont want to see him suffer.... I got him in a hamster carrying cage with lots of bedding, a water bottle and a natural chewable hide hut. His head is stick ****** to the side, he ran for a little bit but is now looking at me. Clearly I do not want to keep a wild chipmunk as a pet, but is he okay to let back in the yard? We have cats and i dont want to see them go at him. Any idea whats wrong with him?