E.B.
On a practical level, when my son hits these phases (where his behavior just seems to deteriorate and he's constantly whining and cranky and sassy), I first look to his "needs"--my son acts very poorly when he's hungry or tired. Has he been staying up with older sibs? Playing hard and skipping a nap? Getting up earlier? Is he growing, and needs a snack before supper? A bigger breakfast? If none of these are the issues (it truly is amazing how much better my 4 1/2 yo acts AFTER a late supper than before), then I decide to work on ONE issue and leave the others by the wayside, temporarily. For example, right now, my son says "poopy butt". It drives me CRAZY. I hate it. But I hate even more that he pushes his little brother out of the way when he's anywhere near his toys. So...I punish and talk to him about his brother; I simply frown and ignore him when he says poopy butt. Once we're on a slightly more even keel with his brother, we'll start on language. But--I realized that I definitely get farther with praise, and limiting the amount of yelling I do gets me farther--he feels better about himself and his relationship with me and is much, much more willing to work with me. Good luck! Those phases are frustraating...