The pain could be associated with skeletal or cartilage as part of the rib cage...that would be most likely if you change sitting or standing position and take a deep breath. More likely the problem is associated with the respiratory system caused by pulmonary thrombosis (clot) and/or lung embolism. That would be the worst case scenario...there are many causes for your symptoms and you should have an exam to evaluate and dismiss any serious heart and/or respiratory disorder.
Hope this helps. Take care,
Ken.
I tend to agree with Ken. I also had costochondritis that was pain in rib cartiledges and once I had to be admitted to a heart hospital overnight for observation. I was OK. But an evaluation of heart was done before I was discharged. You may go to Dr . and go for TMT ECG.