Pulled the Muscle Under my Implant - What Can I Do?

First call the surgeon or see him. Second be patient the pain is from intercostal injury and takes a long time to resolve. Third, get the BF to stop hugging you TOO hard.

From MIAMI Dr. B

There may be a variety of reasons for your symptoms but as Dr. Aldea mentioned if you are experiencing pain with breathing, you should seek emergent evaluation. Most likely this is due to a muscle pull or strain of either the elevated pectoralis major or underlying pectoralis minor or intercostal or serratus muscles.

If you are feeling the pain on your chest wall, deep to the implant itself, then most likely you pulled an intercostal muscle ( the muscles between your ribs).  The good thing is that you did not harm anything in the long run.  The bad thing is that it can take a few weeks for that pain to go away.  Just be patient and it should take care of itself.  If it persist more than 3-4 weeks, you should check in with your plastic surgeon. I hope this helps.