DS is 3 - had his pre-school booster on Wednesday. I've just got in from work and taken off his t-shirt and one arm is very red, swollen and hot - the swelling is about 8 cms long. The HV said to expect a swelling up to the size of a 50p piece so this is about four times that size.
Anyone had this? Should I be worried? He is fine in himself, quite normal but says his arm does hurt.