Hard immovable lump behind ear on the bone

Hi everyone 

I have been freaking out recently after I found a hard lump (less than 1cm) behind my right ear. The lump is on the bone behind the ear and it feels attached to the bone. There is no pain with it. I have googled it but I guess google makes a big deal out of everything so I am trying to stay off it. 

I have no idea how long the lump has been there for. 

I have an appointment with and ENT specialists in a few days but I just wanted to know if anyone else experienced this. 
 

Many thanks in advance