How old is your dog?
When did this start?
What color are his gums?
When did he last eat?
Any increased thirst or urination?
Any head tilt?
Do his eyes move back and forth really fast?
Any recent weight loss?
Any toxin he may have gotten into like antifreeze, rat poison?
I am concerned that your boy either has gotten into a toxin, has a liver condition that has yet to be diagnosed, heart issues, or may have Addison's disease. Less serious cause is an ear infection. He really should be seen as this could be a very serious sign. Your vet will likely run bloodwork on him if nothing outward is noticed (ear infection). If you can get him into the vet tonight this would be best while he is having active symptoms.
I wish I could give you more exacts here but there is just not enough to go on. Please be sure that he had no access to alcohol or antifreeze.
I am so glad you took him in.... I hope he will be fine. Keep me posted.