Just go look on some of the questions on Bradley I'm sure you'll find the answer there
Malnutrition is not having enough of the needed nutrients (not having a good diet, eating a lot of unhealthy food but still eating) this could be from either under consumption or over consumption. While under-nutrition is when someone eats an inadequate amount of food for an extended period of time (not eating enough food in general).
Itchiness I think or rashes