Doctor Found a Dark Shadow On My X-Ray and I'm Really Scared

I found chest pain last week. I went to the doctor and he said it seems like Inflammation. But then he told me to go and do an x-ray on my chest on the bones. The results came back that he found a dark shadow in the middle of the chest. I cried immediately and my mother is really upset and worried too. I did some research and it results to bone cancer. I really don't want that word.
I hate that word. The doctor unfortunately could not tell what it is and he told me to do a bone scan as soon as possible. I am really scared for my life right now. There's no history of bone cancer in my family. What can a shadow be in the middle of the chest that relates to bone? I don't have lung cancer. Also, I'm only 24.