You can use either, but I prefer to only use a sidecheck. Before you use any do some research on how they work, and how to use one. Isnt this the same donkey you were having problems with just a week or two ago?
Mhm, I walked her around in the ring, once, and after that she dose fine as long as the whip is right behind her. but she puts her head down on me, like really low. I have only ever used a Over Check.