A bump on the head may cause a goose egg. Actually any injury on the head of a child is not very bad as the skull often protects it. However, any bump on the head should be properly examined. What caused the bump? How serious was the hit?
If bleeding occurs just wipe the head with a clean towel and examine the injury. Bleeding is a good sign as there may not be internal injury.
A goose egg on the forehead heals quickly. A day or two is the most.