I can understand your apprehension. Masturbation does not cause weakness. However, after masturbation body does get very relaxed. Thus relaxation is often mistaken as weakness by many. Thus the attribution of "weakness" to masturbation is seen very commonly. The rest of the symptoms can be explained by the presence of underlying tension/stress on mind and body. We need to consider associated problems of anxiety depression, stress, etc. Loss of sex desire is very natural as much of sexual energy is utilized while masturbation. I strongly suggest to see a sexologist as he can help you dealing with stress and with the masturbation habit. Regards Dr Pankaj Borade