I'm not sure what you mean by drop of motion. My kids would often catch a second bug soon after recovering from something 'big'. General malaise, nausea, etc aren't uncommon for most viruses.
Did your dr tell you about the BRAT diet? Basically, it's easy to digest foods that should be used in frequent but small quantities when a kid is feeling sick to their stomach. Bananas, Rice (cooked with a little extra water, a pinch of salt and a pinch of sugar), Applesauce and Toast are the "BRAT" recommendations.
If she seems dehydrated (dark urine, several hours between needing/able to go and fewer than 5 times in 24 hours) she may need IV rehydration.
Give her popsicles, broth, watered down juice, and gelatin to try and get fluids into her. Good luck!