It could be the numbing agent if your doctor used it. I always have a reaction to the numbing med NOT the steroid for a couple of days. And I say this because I asked my own PM a long time ago why I would have the jitters that bad and he said it was probably the Marcaine or Lidocaine; whatever it was LOL. And I think he was right because the jitters went away within a couple of days. Normally, the steroid doesn't start working right away...takes awhile for it to kick in. And I have noticed this as well when using just one Lidoderm patch; my heart will race and I get jittery.