Right abdominal rigidity can be due to various causes,however since sonography
has come out with negative reports, this would rule out major changes. However it would be advisable to get an abdominal CT scan done to look for any hidden changes which could not be revealed through ultrasound
. Plain xray of the chest is also advised to rule out any underlying lung infection
which can mimic such symptoms. Any other associated symptoms should also be consulted with the concerned physician. Hope this will help. Regards.