I have a small lymphoid behind my right ear,do not hurt or bother me ,isn't that a sign of infection?

Small lymph node: A small palpable lymph node behind the ear does not necessarily indicate infection. Lymph nodes perform immune surveillance by making antibodies against foreign things like bacteria, but doesn't mean you have an active infection. If you have ear piercings, for example, bacteria can get into the body via the piercing sites and cause a persistent reactive lymph node. I would recommend seeing MD.