My 3 Year Old Son Has Blue Lips, Cold Hands

My 3 year old son has blue lips, cold hands and feet, mottled skin (with goosebumps) but no fever. He has a jumper on and under a warm blanket for the last half hour but isn't changing. He also has had diarrhoea the last 2 days.
He doesn't seem sick but is less active than usual and less hungry.