My daughter has a mass on her head

I recently found a lump on the back of my one year old daughter's head that was about the size of a pea but it's really hard. I didn't see it going down at all so I took her to the dr and they sent us for an ultrasound because it didn't feel like a lymph node. It was a torturous process for my daughter and we got results today that it is a mass and have to see a neurosurgeon for further imaging and examining. Has anyone gone through this with their child? I'm so scared of it being something really bad even though the dr says it's nothing to worry about. That I shouldn't be worried about whether it's benign or malignant. How do you not worry about that? 😔