Our brains are very powerful, sometimes it can even fool us into thinking something is happening when it really isnt.
In medical terms, its called a placebo effect.
Without doubting that something comes out of you, and regardless of what it is, your brain is temporarily tricked into thinking that whatever it was is what was ailing you in the first place. Soon, you're body catches up to your brain or vice versa and you realize you still have the original problem.
Think about those who lose limbs, who report some type of phantom pain or some other sensation on the end of a limb that isnt even there any longer.
They look down and their eyes can see that their foot or hand isnt there, but their brain tells them that it is because it can sense something that their eyes cant see.
As I've said before, our brains are very powerful and often can do things that defy explanation. Science tells us how the brain works and gives us really cool animations on how thoughts are produced etc.
But quite honestly, nobody REALLY knows how our brains work and why it does what it does.
The day they figure that out, will be the day that medicine Science and human health will change forever.