Hard non moving lump on bone behind my ear

Hi All, 

I am going out of my mind with worry. 
recently I noticed a lump behind my ear, I thought it was just a spot. Tonight I felt it again and it feels hard, smooth, on the bone (instead of just under the skin) and doesn't move.

I was already at a very anxious point as my daughter was just diagnosed with epilepsy. With this, it's sending me over the edge and I am petrified.

I am calling to see a doctor tomorrow. 
If there is anyone who has had anything similar and it turned out to be ok, please let me know. 

I'm so scared of not being around to watch my little girl grow up.