what is the read up of the patient after retraction's in supine are given? Does the patient have increased pain in loaded position?Also important is,what was the position of the neck when the child decided to swing on it. Since you have already started with retraction,you have already introduced flexion to the upper cervical spine. If this has not given you any positive outcome, try out upper cervical extension, which can be seen by introducing protrusion or by isolated upper cervical extension. Then if necessary see what the movements in the frontal plane are throwing up. The diagnoses could be many, but more info is neccessary regarding the case.