Taking care of your health IS every bit as important as getting some regular exercise. You will not derail any of your efforts at good health or weight loss because you have to take a few days off from your routine to take care of yourself.
The fact is, if you're fatigued and not feeling well, exercising is the last thing you should do. Could you get in a work out ? Sure, but it wouldn't be productive. You're also at a higher risk for injury because you're fatigued. It's okay to take a few days off to REST. As you start feeling better and have a bit more energy, you can slowly ease back into a routine.
But for now, it's time to take it easy. get plenty of rest and push those fluids. Like everyone is saying, taking care of yourself when you don't feel well IS a part of a healthy lifestyle.