Hello there I have read through your question and understand your concern. Since you don t have any history of injury, it rules out fracture. Most Likely you have developed a pulled muscle due to faulty posture or faulty position of sleeping. If that be the case the pain will subside on its own in a few days. You should do mild stretching exercises and can take over the counter painkiller like advil. Another cause of pain in the ribcage is costochondritis, which is inflammation of the cartilage connecting two ribs. It can be diagnosed by physical examination by an orthopaedic. If you don t experience any relief in two three days you should get your self checked. I hope that answers your question. If you have any further questions please feel free to write. Thank you for choosing healthcare magic.