I posted about this in the Oct 2012 boards but perhaps some other Bee's can shed some light on this.

I took N on April 4th for his 6 month appointment. Here it is April 22 and in the one leg he still has a lump and needle mark. The doctor is not at all concerned, in fact they said it was normal. I am not normally one to be too alarmed about a lot of things but this bothers me! When we arrived at the doctors office it wasn't there but it is now and hasn't gone away. He received the DTAP shot in that leg. It doesn't seem to bother DS at all but it bugs the heck out of me...

Does anyone have experience with this? Any suggestions?