Re: Ice Breaker :-)
My youngest gets knots from his vaccines (especially Prevnar). They don't hurt him after the first few days, though. I massage the area while he's in the tub. Last time, the knot lasted 4 weeks. He still has his knots from his 1-year shots that he got last week.
My ped said that it is a "normal" reaction to the vaccine. That it is a side effect although not one of the most common ones (fever, grumpiness, etc).
Hugs to your little one. Call your ped if you're concerned.
Mama to Riley (06/02) and Brayden (04/05)