Problems with my cherries.........

Hi this is my first time here and I am quiet new to gardening but am giving growing fruit & veg a good go this year.  Last year I planted a cherry tree in the back garden, this year it produced flowers which in turn turned to fruit.  The fruit is now about as big as a large peanut and is starting to go yellow with some brown patches.  This is spreading slowly but is definately progressing.  I water it every day but have not fed it with anything at all.
Can anyone offer any advice please?