whether its nevous weakness?

hi all
i was doing masturbation for 7 years. my  problem is i was not able to masturbate

if do masturbating i was not able to do my regular work for one week. i feel tired and
my back spine and hands and legs are trembling a lot.

whether its nevous problem?
am under going treatment for past one year. they telling it may be due to impotence. but still its not cured.

whether can any one give me some suggestions to see which doctor to see.
and also whether it is curable.