It will be an up and down. I ALWAYS bounce in a 5 lbs range. Don't fret. So many things effect your weight. Do your measurements to, those change pretty fast to start with. Then sometimes those will change when the scale seems stuck.
Don't get discouraged, as long as you are following the directive the doctor and nutritionist gave you then you will be fine!
Like so many people say this is not a fast journey. Some lose faster than others, but what matters is losing.