Hi, Welcome to Health Care Magic, thanks for posting your query . I understand your concern. Masturbation is quite natural in your age group and it has nothing to do with the shivering problem that you are facing. It might be related to a anxiety issue or you may be under a stress of some kind lately. I suggest you to meet a physician who will be able to evaluate your symptom and examine you thoroughly . Please get a nerve conduction test done to rule out the nerve related causes of your symptom. Also if you are in a stress/ if you feel nervousness most times its better to consult a psychiatrist to help you relax . Do eat healthy and include a high protein diet . Hope this helps , and answers your query satisfactorily . Do write back to us if you need further assistance . Take care , Wishing you good health . Regards.