usxuk-headcanon:

England has a constant cough and it gets worse when the Moores Overflow in the rainy season. This cough can range from a “grunt” to full blown coughing and the stuff that comes out is the moores. When he is sick the coughing gets worse and he can’t breathe. During the rainy season or when the moores are more prone to over flowing he goes to stay with America who knows the procedures to take care of him (if America is unable (which is rare, Alfred makes a POINT to be free during that time) its France). 

America worries constantly about Britain and if he’s doing ok all the time but hides his worry with jokes. In his suit case he always has the meds needed to care for Britain should an “out break” occur but Britain never knows it. 

Britain is also too stubborn to literally ask for help so America has come to know what certain things mean. And he’s gotten pretty good. When England is really sick from them, he won’t admit it out loud but he likes to sleep in America’s bed cuddling with the younger country so he feels safe and knows that if he would wake up coughing in the night unable to breathe America would be there to help him.