Well an Xray is not going to show any stress facture. It would rule out any major fracture or pheumothorax (which is impt to rule out if associated with a fracture). Quick tricks for looking for a fracture include a quick run of ultrasound over the boney region (pain might well indicate fracture). Obveoulsy you would not then continue with the U?S as a treatment! Also the vibration of a tuning fork held adjacent to a fracture that is close the the skins surface can indicate a fracture when pain is provoked (due to vibration in the bone).

Costochonral joints can indeed sublux or "pop out" and rather easily in competitive sport. You would compare obviously visually the right with the left in standing and perhaps in lying as a rotation through the rib cage would be more obvious.

You would still check the back itself as a constcondral subluxation probable has a disruption to the costovertebral region as well. Thus the Tx might need to be addressed with manual therapy in some way.

Supporting an inhalation to assess the best direction of force to help reduce the pain. You can then use this as a treatment either in sitting, supine or side-lying to help relocate the joint position if it appears on palpation to be out of place.

Address the trauma as you would a bruise. Supportive measures such as a bandage around the chest or taping can help if manual support has already proven to reduce the pain.

8o What course are you actually studying?