Sharp, stabbing, mystery pains happened to me all the time-- in various places. The worst was in my shoulder (deltoid) muscle. It hurt for a week and sent me in for an MRI. This happened back in October. I thought I had seriously injured my rotator cuff, though there was no moment of injury!
The MRI showed nothing! ....of course, and the pain went away on its own. Amazing that Lyme can cause such serious pain. At least I'm convinced it was Lyme. No other explanation.
A few days ago my OTHER shoulder had the same exact pain. Excruciating! This time it lasted only 24 hours.