All of this happened because of some structures in the brain called the limbic system. The limbic system has control over the expression of emotions, instinctive behaviors, drives, motivation, and feelings. It links all of these intangible things to a motor expression or behavior. In my case, it was shaking and an inability to speak, but there is always an output to our feelings, even if you can't see it. That is the limbic system in action.
Animals panic when they smell death.
It is an instinctive behavior. And there is a type of moth that will travel half the length of California seeking out its ideal mate via smell. Humans are not exempt from the powerful effect of smell on the limbic system. Every time I smell warm, homemade chocolate chip cookies, I remember the same thing. I remember running in the door, and chasing the smell to the kitchen.