Could The Leg Be Free From Hair Line Fracture If There Are No Symptoms?

my 4 yr old jumped off the bed and injured his leg. He couldn't bear wieght on it. Took him to the orthopedist and xray was clean but that it could be a hairline fracture they dont see. They told me to come back in a week for another xray. 4 days later after staying off his feet he feels fine. could he still have a hairline fracture or was it probably sprained?