What is wrong with a dog that suddenly jerks and gets stiff and then gets better?

A dog’s sudden convulsions of stiff limbs after a while can be caused by the following reasons Firstly, calcium deficiency. Secondly, fear and anxiety. In this case, the owner has to calm it down. Thirdly, illness. For example: epilepsy, distemper. In this case, take the dog to the hospital for examination and treat the symptoms.