A is 16 weeks, so had 3-month jabs 4 weeks ago and should have his 4-month ones week after this (once a cold clears up).
Just seen a huge (ok, 1/2 inch across, 1/2 cm high) red lump on his left arm about where the jab was. Any idea what it could be? I thought any reaction to a jab would have been way earlier and this can't have been there more than 2 days.
Any ideas?