Does fat loss slow/stop when you're sick?
you tested the waters using a high intensity routine?!
DEFINITELY start out light. Especially if you have any history of chronic fatigue, hormonal issues, weakened immune system, etc.
You shouldn't simply go all out because you are tired of NOT lifting. You should return because you feel better.
When you feel better, start out with modified form of your regular workout. If that goes over well, you can progress to your normal training program (preferably not metabolic training) during your next session.