Whats wrong with my dove?

my dove is a homing bird it usallly would fly and then come back to its cage outside and it used to coo.but now it doesnt coo or fly it jst flys when its scared.i gave it apples and carrots and some rice but it wont eat.its just sitting in the nest that i made for it.it just sits and lays down over there.im worried it doesnt have a vet cause i cant afford to take it to a vet.im doing the best i can.but every time i go near it it just flys away cause its scared.it hasnt been cooing or flying for about 4 days.it just sits in the nest and then at night it sleeps.its windy where i live.espiacially at night.it warm sometimes but i dont know what to do.it looks okay but it doesnt coo or fly someone please help.