If the chest x-ray truly is
normalNormal saline flush, then this pain that only occurs with sneezing is probably due to a strained or torn muscle or
ligamentAnterior cruciate ligament (acl) injury
Tendon vs. ligament within the chest wall, around the
ribsRib cage pain. Another possibility could be a pinched
nerveNerve biopsy
Nerve conduction velocity in the chest, along one of your
ribsRib cage pain. This type usually occurs after a fit of coughing or a blow to the chest. Finally, this pain could be due to a nerve being pinched, where it comes out of the spinal canal. X-rays of the spine can usually give a clue to this cause.
For the moment, you should give this pain time to spontaneously go away, and in the meantime, try to hold your chest with both hands over the site of the pain.