36-year-old woman experiencing postnatal back pain

The patient is a 36-year-old obese woman who presented with upper right back pain 10 days after a normal child birth. Pain is worse on coughing. Otherwise, she is fit and well.

Upon examination, you find:
No shortness of breath
Normal oxygen saturation
Patient is afebrile
Auscultation: Reduced breathing sounds in right base, fine crackles on right
View the image taken and consider what your diagnosis would be.