I'm sick

This morning I was sitting on the couch, and I guess the white blood cells must have given up or something, because all of a sudden I was sick, just like that.
It's weird, but why do we get sick? What is the point of sitting on the couch feeling awful with your head pounding and your heart-rate way up? How does that help anything?
I know this sounds like the constant question, why does god let murders happen, or why does god let people go broke, and stuff like that, but there is a difference. Humans created the guns that cause people (Some) to be murdered and are the murderers themselves, people create the money that people lose. I'm not saying that money itself is evil and that humans should never have created it (Although I am saying that about guns), but there is a difference. In those two instances, it is a human action, not a metaphysical action, that caused pain. But disease is a natural thing, so why did god create it in the first place?
The obvious answer is to keep the population in check, but what kind of god who loves all his people would allow them to be thinned out just for the sake of preservation. Why not make us not have too many kids?
Because that would be too easy.  it is part of the human condition that we need suffering and pain and even death to truly understand things. We can't all have it given to us on a silver platter. If we were never been given problems to overcome, what is the point of living. What fun would it be to watch a movie in which nothing ever went wrong? it is the same with life. And disease is an opponent we can never kill. Sure, we can hand out vaccines and have all the medical attention we want, but disease keeps mutating to penetrate our defenses.
I'm not saying here is anything good or fun about death and pain, but it is a reminder that we are all mortal, and no matter how far we advance, we will have to keep facing the same old nemesis.