Hi My 2year Old Daughter Was Diagnosed With The Gastric

Hi my 2year old daughter was diagnosed with the gastric bug 1weej ago , she is still vomiting after everything she eats or drinks , her nappy is like a white clay colour, She crying with her little tummy and has no energy to do anything she basically sleeps all day on the sofa , she is not herself atall , she is losing weight and has dropped down a nappy size as well , she is totally worn out , she I be concerned she still has it and losing weight and that her nappies are not normal ..