My Dr Ordered A Chest X-ray Because I Was Complaining

My Dr ordered a chest X-ray because I was complaining about hypnic jerks. My hearts stops and body jerks whole I'm just sitting or laying down. The start came back showing that I had a spot on the film and I was told to retake the X-ray that it might just be showing as a spit because of the way the X-ray was taken. When I did it over the X-ray showed the same spot so now I've been ordered to take a cat scan. What could this spot mean ?