You need to set up a hospital cage. Tent 3 sides and the top and put a heating pad on low under one half.
Move all your perches and food low or on the floor so that your bird does not need to expend energy trying to get around.
Two of the most important things are heat and hydration. If you have any clear pedylite you can mix it in his water 50/50.
If your bird is sick you will need to get him to the vet tomorrow ASAP. Do you have a vet or can we help you locate one?
Tell us where your at. Just city/state/country.
Ginger