My son had surgery today to have a lymph node in his groin removed. During surgery he had an allergic reaction and had breathing issues. His eyes were swollen shut. He's been home around 8 hours now and his face and eyes have been normal. In the last hour his eyes have now developed what looks like a rash around them and the redness is running down his face. I feel like it's another allergic reaction coming on. How do we know when to be concerned.