The Master Cleanse is a kidney flush (as well as being lots of other things). So you've already done one!
You don't HAVE to do a parasite cleanse before doing a liver flush, but if you do have parasites in your liver, it is better to get them out before you flush. Your call.
ALSO, I strongly suggest readjusting your body to food before doing the liver flush. You can do one immediately after an MC, but it could be "shocking" to your system.