Hello, and thank you for using Petco Pet Education Center, formerly Petcoach. Poor Joey! It would be helpful to know more about what sort of trauma Joey experienced and what you’re observing with him now. Joey could have a minor concussion or headache that could resolve simply with rest and time. However, more severe head trauma can cause bleeding or swelling in the brain, which can be life threatening and must be promptly treated by a veterinarian to minimize damage. For this reason I strongly urge you to bring Joey in to the vet immediately, particularly if he is acting painful, confused, squinting or shutting his eyes, stumbling, or showing any other alarming symptoms. I hope this helps and I hope he’s alright!