Keep up the good work! My doc lets us start mushies at a week, and I was like you--dropped 15 pounds in the first ten days.
For me, the weight loss did crash to a halt when I started mushies, and I even went up a couple pounds. It doesn't make sense from a calorie standpoint, but remember that your intestines are probably all cleaned out after a couple weeks of liquids.
For me, I know I've been exercising and my muscles are sore, which always means a little water weight gain for me. Just keep going and believe that the weight loss will come!