**HELP**

I'm a FTM and I need some help putting my mind at ease. My 5 month old son has a bone like bump on the back of his head (circled in the picture).

It isn't on the opposite side of his head and if it is it definitely isn't as prominent as the one I've noticed. Have any of you mommies noticed anything like this on your babies? I'm a worry wart and automatically assume worst case scenario. You can even kind of see the lump in the picture... (it isn't a lymph node)