DD had pre school boosters yesterday. On the arm that the DTaP/IPV went in (the other arm was MMR)it is swollen, red, very hot and feels hard. When you compare her arms you can see its gone bigger than the other one. The affected area goes from half way up her bicep to the very top of her arm (a good 3-4 inch circle). Is this normal? Does it need to be looked at? It just seems quite fierce at the mo...