When was your miscarriage? It could show up for another 3 months, I had that with my second pregnancy, if the mC is not to long ago its very very likely its from the shot. I think you can relax. even if it would be from that pregnancy it probably wont harm the baby since they start out as the kind that cant cross the placenta and turn into the kind that can cross between I think 2 to 6 months. I formed mine most likely at 12 weeks with my last child ( I had bleeding, and nobody thought of the shot) and my son was just fine.