How To Treat Painful Bumps Behind Ears?

Behind my ears, and on my neck hairline I get bumps that are sore and when I pop them white really smelly stringy stuff comes out. It's like there are pockets behind my ears because sometimes warm water makes it come out by itself. Sometimes it is really painful- like I have been hit in the back of the head. I also have soreness under my armpits but dont find any pockets there. This has been going on for about 8 years and my doctor says that it is my bodys way of fighting off infection. Is this true or should I be worried about something else?