Suggest Remedy For Penis Problems

my friend has a severe penis problem but being ashamed and scared he didnt ask anyone- he started watching porn at the age of 10. he used to get regular erections but at 12 he got got somewhat hyper and started rubbing his penis. then he got a sudden uncontrolled flow of sperms. since then whenever he got an erection sperms would flow automatically but thats not the end of it he started masturbating at the age of 15 then he noyiced that the length of his penis became smaller gradually from around 15cm to 6-7 cm what can i do to helphim is there any solution he is currently 15