This may be related to the food in that the food may be triggering allergies or make him more active leading to the problem.
But its also possible this is a neck issue seen in the breed or an inner ear problem also seen.
You can read about episodic falling here
http://www.cavalierhealth.org/episodic_falling.htm
and the spine issues here (long page - scroll down)
http://www.cavalierhealth.org/syringomyelia.htm
You may find this recommendation on feeding help usful
http://www.cavalierhealth.org/diets.htm
My personal preferences for foods are foods with high quality ingredients limited grain and protein sources. For example the EVO red has a lot of protein sources so if one bothers the dog trying to eliminate which one it is would be difficult.
My particular dogs appear to do best on a chicken and rice based diet but you may find something else works for your dog. You might check out California Natural, Blue Buffalo, Diamond Naturals or your dog may do best on a diet such as the above site suggests you investigate.
The one thing I have learned about diets for dogs is the important thing is does it work for your dog. My dogs may do great on chicken but your dog may do better on lamb, fish, venison etc.
I prefer 26-30% protein and 16% or less fat but I limit the amount fed and the dogs may get some extra fiber like carrots to chew on.
Hope this helps you!
Dog Expert:Rescue, Train,Breed,Care
30+ yrs dog home vet care & nursing, rescue, behavior&training, responsible show breeding, genetics