The Shock Shield grip might be a good idea. I'm using the stock PK grip. I still think the issue is the weight of the racket. I used the heavier PST before the 7G and it just got to be too much after awhile. It seems like the same thing is happening with the 7G now.
The Shock Shield grip might be a good idea. If you try it, don't be discouraged by the larger grip size because it will compress after a few sets and feel normal sized after that. If it turns out you need a lighter racquet, PK just started selling the Q5 295 version. It's a bit stiffer and more powerful, too, so it might ease your transition to a granny stick.