I know this is a common theme with GT kids, and may well be part of that, but have you looked at food intolerances?
My DD4 has an intolerance to dairy and soy. Although she can be intense a lot, when she has either of those 2 things she is completely awful and unpredictable. It took a lot of trial and error to figure out what is was but so worth it.
Also I keep getting people asking me if dd has hit the awful 4&1/2 stage yet that girls seem to go through. I tend not to put too much stock in ages/stages but it could be that your dd is going through a normal development spike which is compounding the gifted stuff.
DD responds quite well to us being very firm with what we won't tolerate. We don't punish, but I will say something like " I don't deserve to be spoken to like that so I'm not going to listen to you until you have calmed down" or some such phrase that suits the situation. I then carry on with my day and the ball is in her court.
