According to the major symptom you describe (stabbing pain on the rib, just under the right breast), you are probably experiencing what is called a pleural pain. Pleura is the outer cover of the lungs). When there is an infection of pleura (pleurisy), infection of the lungs (pneumonia) of a kind of liquid between the pleura’s inner and outer layer (pleural effusion) of different origin, this can cause a sharp, stabbing pain, as you explained (pleural rub). Another possible cause can be a “kidney pain” reflecting on the frontal side. You might want to check it with your family doctor, who might do a physical examination first and then, if necessary, add a frontal and side chest X-ray (and/or maybe even native x-ray of the upper abdomen), to exclude or confirm the cause and treat it, accordingly.