pre-op Diets

HI, just signed up for this site today.  My surgery is scheduled for Jan. 22, I have been on the pre-op diet since Jan 8.  I have 3 protein shakes a day, 2 cups salad greens or 1 cup cooked veg and 3-4oz of lean protein, and 2 1/2 cup servings of sugar free jello.  It is a challenge for me and I honestly feel horrible, I ache everywhere and have a horrible headache! Is this common?  Also I slipped up a little day, I ate more protein with my salad and I had 4 pretzel rods.  I need to stick this out and remember that this is the start of a new life for me.  I just wish I wasn't feeling so bad. 

WHEN I WAS ON MY PRE-OP DIET I USED PRIMER PROTEIN SHAKES  THEY HAVE 30G OF PROTEIN  AND I ATE GREEN LEAFY VEGGIES WITH BROTH, .. I ALSO HAD SUGAR FREE POPSICLE, ALL DIET DRINKS, NO SODA .. I ATE ALL DAY AND LOST 16 LBS IN 15 DAYS... ON THE 16TH DAY I HAD THE SURGERY .. THE REASON FOR THE FLUID DIET IS TO SHRINK YOUR LIVER FOR SURGERY