On Wednesday I Had A Routine B12 Shot Administered, Which

On Wednesday I had a routine B12 shot administered, which I get once a month. My doctor okay'd it to be done two days early so I wouldn't have to come in twice in the same week. I usually experience no side effects with this shot, including during and immediately after its administration.

It felt off to me this time, but thought I was being paranoid and trusted that the nurse knew what she was doing. It is now Saturday and I am experiencing pulling/pinching sensations in my arm where the shot was administered, made worse by lifting my arm. It doesn't really hurt, just feels like someone pulling my muscle or a tendon tight inside my arm. The area itself is not discolored or swollen, either. The shot may have been administered slightly higher than normal, but only by a few centimeters, and the injection is about parallel to my armpit.

I have health-related OCD so I'm becoming incredibly anxious about this, especially because it's a weekend and I won't be able to contact my doctor until Monday. If you could give me some idea of why this would be, and any steps I can take at home to alleviate the sensation, that would be great.

Thank you,
Kyri