32 year old female with no past medical history presents with cough for two weeks, no fever, no sputum. Multiple sick contacts with same symptoms at work. She acutely presents with left rib pain for several days. She reports no trauma, and noted the sharp, positional pain during a fit of coughing. Her vital signs are all within normal limits. She is breathing comfortably, with good air movement, no wheezes, rales, or ronchi. She displays point tenderness over her anterior left 8th rib at the anterior axillary line. A chest x-ray was ordered; images are below.
Sonopalpation of the tender area revealed the following:
Untitled from Sinai EM Ultrasound on Vimeo.
What is your diagnosis? Can ultrasound help? How would you perform an ultrasound on such a superficial structure?
What is your diagnosis now? 
