Everytime i rub behind my ear it's oily. it's itchy and annoying. i'm wondering why its a terrible foul smell?

There's a reason ...: ... your mom told you to "wash behind your ears." Dirt accumulates easily behind your ears as gravity causes scalp sweat, dirt and bacteria to migrate there. Initially oily, it can dry and become irritating and itchy .... and stinky! When bathing and shampooing, be sure to focus your washing & rinsing there to eliminate the problem. Good wishes:)