That's a symptom of itchy ears. May be infected with ear mites, can be treated with Erjingkang. Dogs have L-shaped ears and long hair, which is beneficial to the growth of bacteria. Wash it once a week with ear wash water, otherwise it is easy to get infected.
It could be a heart problem. You just need to see if the dog's heart is abnormal and its mouth is white.
Dogs eating this kind of food by mistake will be poisoned, including gastrointestinal tract, cardiovascular system and nervous system. Symptoms such as vomiting, diarrhea, rapid heartbeat and excitement will appear in the early stage, and even nervous system symptoms such as trembling, spasm and epilepsy will appear in the later stage. Dogs with these neurological symptoms usually have a poor prognosis.
The dog is probably sick! "Shaking dog syndrome" is related to nerve conduction in the brain and is a genetic disease. In other words, this is a hereditary disease, which is common in some breeds of dogs.