Acute rib pain

My wife (53 yo) has had two epsides of acute right side rib pain, R-4 or 5.  In both instances, she bending and reaching when she said she felt a "pop" followed by immediate intense pain.  She is tender on the lateral aspect of her chest.  Respiration and coughing make the pain worse.  She often self splints.  X-rays performed did not confirm any rib fracture or other obvious abnormality.  Over a two week period, the pain diminished, but now it has happened again.  I would like to get some advice on where I should go next for some help.  Thank You

[daisey16]

it might be costocondritis, which is the cartilage that connects ribs to the sternum, I have had sternum pain for over a year. I'm not a doctor so I don't know if it's supposed to make a popping sound, heart problems can be ruled out with an EKG. If she has a bad back that is popping or cracking that could be cause, try Psysiotherapy?  Hope she gets better