Sharp Stabbing Pain Under Shoulder 2 Weeks Post-op Breast Augmentation

Any sharp pain of that level should be evaluated by your surgeon. However, in my experience the shoulder blade pain can be due to improper posture compensating for the pectoralis pain. Actual pain inthe armpit may be due to pressure on the nerves exiting the chest and entering into the arm. In either case seek evaluation by your surgeon for reassurance. IT could be due to other causes. The exercise video below may help but only after meeting with and approved by your surgeon

The pain you describe is unusual for an augmentation mastopexy. Shoulder pain is often referred from another area and may be entirely unrelated to your surgery. In some cases, a pneumothorax (air around the lung) may cause this type of pain. Either way, I recommend you see your surgeon for an examination. 

This is truly unusual.If the pain increases on deep inspiration you wonder if their is some pleurisy or a sensory nerve that is being irritated.Assuming their is no infection or fever you may want to try a medrol dose pack which is a steroid and can reduce inflammation.

Having such severe pain two weeks after a breast augmentation and lift is not common.  You should speak to your surgeon and be evaluated.

The pain may either be secondary to nerve stretching, edema, or muscular stretching.  It should subside with some time (?length unknown!).

A sharp shooting pain to the shoulder blade can be a sign of a pneumothorax (air around the lung).  This  happens when a hole is made through the outer covering around the lung.  The muscles between the ribs are thin and this can occur when breast implants are placed under the pectoralis muscle.  It's rare, but a chest  x-ray will diagnose it.  The hole usually heals up and the body absorbs the air within days.  Even more rare would be a blood clot to the lung.  A collegaue of mine saw this in a healthy 24 year old following an uncomplicated breast augmentation.  The particular pain you are describing bears further evaluation at this point.

Pain as you describe can be caused by a nerve which is stretched by the implant. It is uncommon. With analgesics and anti-inflammatory medications it usually improves. Sometimes it is necessary to prescribe medicines which can improve nerve pain. A visit to your operating surgeon is in order to see what might help.