Why Does My Dog Keep Doing With Shaking His Head?

It is normal for a dog to shake his head occasionally-perhaps a few times a day.  It is not normal for constant shaking or scratching.  This can be a sign of allergies--allergies in dogs often manifests as skin disease and ear inflammation/infection.  Dogs can also get foxtails, grass awns, ticks, or other foreign bodies in their ear canals.  The veterinarian should look down his ears with an otoscope to look for foreign body.  Some dogs need to be sedated for an otic exam, ear flush, and foreign body removal. 
An ear cytology should be performed to determine if an infection--yeast, bacterial, or both--is present.  Ear mites can also cause discharge and scratching.
Your veterinarian can diagnose the problem and provide appropriate treatment.

Probably a foxtail or ear mites

Sounds like your dog has an ear infection...if he keeps it up he should see a vet...my brother has a Lab that gets ear infections all the time and does the same thing

The dog is experiencing pain like a headache. You must talk to his veterinarian to find out what would be the best way to handle this. I think that the dog need lots of water, but please ask his vet.

My miniature poodle I just got a few days ago keeps shaking her head after a nap and it seems like she can't walk right, is this anything serious I should take her in for right away?