Dear Welcome to HCM We understand your concerns I went through your details. Please understand masturbation is natural and cannot cause any health issues if done in moderation. For young adults one per day and further thrice or four times a week is considered moderate. The pain you are complaining of may not due to the masturbation. But the neck and shoulder pain could be due to the anxiety associated with the wrong information you have about masturbation practice. Due to masturbation, your nerves and veins cannot become weak and you cannot loose weight due to that. But, if you are anxious about the whole things because of your wrong knowledge base, you can have all these symptoms, and understand, these symptoms are not physical and are psychological. Please consult a psychologist for counseling. If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR. Make sure that you include every minute details possible. Hope this answers your query. Available for further clarifications. Good luck. Take care.