I really feel you on this, being a first-time mum and noticing something new and unexpected after a vaccine is genuinely unsettling. A bit of soreness at the injection site is pretty common, but the swollen lymph node near the collarbone is something I would not just brush off, since it is a little further from the injection spot. I think it would be good to bring this up with your doctor or the team at KKH, just to be safe and get some peace of mind. They will be able to tell you whether it is a normal immune response or if it needs a closer look.