There are many possibilities for adult cats to cause this symptom, such as cardiac hypertrophy, calicivirus infection, food poisoning, etc. They need to go to a regular hospital for investigation before the diagnosis can be confirmed. This symptom in growing kittens may be caused by cranial nerve problems caused by excessive ear mites, lack of vitamins and calcium, but the cause of the constant shaking of the head and legs and loss of balance needs further confirmation.