[tile health is critical]
I should have canceled all classes in the morning. I know teaching will worsen the situation. But I was worries about the consequences of canceling class with short notice. So I went to school anyway.
It was exactly as I expected. After teaching two classes, I was drained and caught fever. I had to cancel the rest two classes, in even shorter notice.
Next time, set your priority right: if you are sure the cost is more than the gain, just cancel it.