Thanks for your query.You are getting dull aching pain in testicles .and in spermatic cord
.This could be due to mild varicocele
and can be confirmed only on clinical examination.So please consult some surgeon for examination and confirmation Please get your color Doppler study of testis and cord done this will confirm the diagnosis.As regard your doubt about any kidney
problem please note that testis has nothing to do with Kidney.Whatever pain you get in kidney area is called as referred pain
Since you have dull pain and you are 65 years old you do not need any active intervention Do not worry about it If it bothers you too much you can use scrotal support so that your testicles will not hang down This will help you and give relief from pain.