Sharp pain after breast augmentation. Have I pulled a muscle?

Relax.  It is only very early after your surgery and it is normal to have pains similar to the one you describe.  Any submuscular technique (including dual plane) involves some cutting of the pectoral muscle - in effect this is a torn muscle - so it is common to have some discomfort on certain movements that stretches the muscle.I would expect it to settle down over the next few weeks.  If you have any increased swelling or pain, or it simply is not improving, you should contact your PS.Kind regards,Dean

Don’t worry, pain is normal even 7 weeks after a revision. Regeneration of the sensory nerves is accompanied by tingling, burning, or shooting pains which disappear with time and are nothing to be alarmed about. If, however, swelling, redness, infection, or drainage accompanies this, then you will need to see the doctor at the office. Nipple numbness may or may not persist, but usually comes back within a year.

In the absence of major size increase-chances of a serious problem are minimal. Follow your doctor's post op instructions and stay close in touch with him and the office

This is a common concern for women after breast implant surgery.  The submuscular placement can result theoretically in muscular sharp pains that are transient and dissipate with increased activity and time. The dual plane technique is although possible, if done as originally described, does not typically add any discomfort to our patients.  I use this technique specifically when one's breasts have some droop or ptosis.  Usually ibuprofen and slow gentle active range of motion will help alleviate any muscular pain in my patients. 

Given your implants are under your muscle, most likely these pains are just related to normal healing from surgery.  Part of that muscle was cut to have the implants placed, so certain movements early in the recovery, will cause pain and discomfort.  Continue to follow with your plastic surgeon and good luck in the rest of your recovery.