While loops in while loops don't work. Help?

My attempt at making a platform that goes back and forth is considered to be a failure. Is it okay to put a while loop in as while loop? This is my code:

while true do
	while true do
		script.Parent.CFrame=script.Parent.CFrame+Vector3.new(0,0,.5)
		wait()
	end
	script.Parent.BrickColor=BrickColor.new("Bright blue")
	wait(5)
	while true do
		script.Parent.CFrame=script.Parent.CFrame-Vector3.new(0,0,.5)
		wait()
	end
	script.Parent.BrickColor=BrickColor.new("Bright orange")
	wait(5)
end

Put these inside the main loop to replace the other "while " loops

coroutine.resume(coroutine.create(function()
while wait() do

--cframe stuff

end
end))