My toilet is loose and rocks back and forth on its base. Do you have any suggestions for correcting this?

A tippy toilet is a cousin to a leaking toilet, if left alone it will begin to leak soon. I usually recommend tightening the floor bolts first to see if this helps. A word of caution here, do not over tighten the bolts or you may crack the base of the toilet flange that holds it to the floor. You may already have a cracked flange which likely means you will need a plumber or do some plumbing changes yourself. If tightening the bolts does not help it is possible that the flange is not level with the floor. The drain plumbing and floor may need to be cut open to make the necessary repairs. Hopefully this is not the case as changing the drain plumbing which is all glued in place becomes a fairly large job depending upon where the toilet is in the home. Good luck.