masturbation

Hello dr. Avramov.. I"m writing in english and its not my first mail to you, in past i mailed you to. but i have now a diferent question. My very good freind (that is married and 61 years old) have no sex with his wife over 1.5 year. since we are very good friends he talk only with me about his prob. He dont speak Hebrew thats why i type in english (for him) because he is very shy man. Since he have no sex long time he masturbate. His prob is, every time he finish , next day he have in his left testicle strange feeling and not comfortable. Now he is aftraid to masturbate till the end. Can you tell me what can be the reason about this feeling, and if he can masturbating till he finish? Its worried him very much. Waiting pls for you answer Lisi.