Ok, this all sounds good.
If his breathing rate is normal (less than 40 breaths per minute when sleeping) and his behaviour is normal, then I am not concerned about your little guy.
I have met many dogs with head trauma - from a road traffic accident, or from being hit by a baseball, or by a bat, or even a bean-bag gun. However, in my 16 yrs of practice, I have never met even one dog or cat who did serious damage to themselves by hitting a table of chair or other object. Fortunately, the skull is very strong, and the worst I have ever seen has been a tender bump for 1 - 2 days.
Since your boy is not vomiting, has no blood in his ears, and is resting comfortably, I feel it is very likely that he is completely fine!
I hope that this helps you to not worry about your senior dog
If this has been helpful, please "Accept" my answer and provide feedback.
If you need more information, just click on reply and I will try to provide it!
The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.