Hi, I had gone through your question and understand your concerns. His symptoms are strange and it may suggest many pathologic conditions. If there is no fever, then this is not likely to be of infectious origin. Often, weakness and shaking suggests low or too high blood sugar levels or other electrolytic abnormalities. SO first step would be to do routine blood tests to serach for such issues. Other causes include neurologic ones such as Parkinson or hormonal issues or rehumatologic disorders. If hypogliceima is excluded then extensive evaluation is required to check all these diagnoses. I hope I have answered your query. Wish you good health.