It has happened over the course of 4-5 weeks. His under arm and area around private parts is turning black. and now I can also see skin under his eyes has turned black. He used to have pink skin but suddenly it has gone black. He sits in the sun during the day for a couple of hours. But it doesnt look like a tan since his under eye skin is also black now. Im worried. We got his blood test done but nothing came up.