No. When people start a Keto diet it is very common for them to lose 3-5 pounds very quickly. This is mostly water because carbohydrates increase water retention. The "keto flu" is really generalized symptoms that can include nausea, body aches, irritability, etc. These are due to your body adapting from burning sugar/carbs/glycogen as fuel to using ketones as fuel.
Feeling nauseous or not isn't really related to general health. Keto flu symptoms are common and generally last a couple of days. Staying hydrated by drinking a lot of water (remember you've lost over a pound of water in a day), and replacing your electrolytes (sodium, potassium, and magnesium) seem to help minimize those symptoms. Avoiding strenuous exercise and getting adequate sleep are also advised.