Whenever you get sick, you experience two types of symptoms.
Physical symptoms and negative emotions associated with that pain. In the case of a cold, you get high temperature, cough, muscle cramps etc. also your emotions will match the pain you are in. You might feel sad, isolated, your emotions might fluctuate a lot etc.
What is so interesting about mental health is that you get the emotional symptoms as if you were substantially damaged but you don't get any localized pain or physical symptoms.
The conclusion so far was that it is all in your head. If you look at the most popular forms of therapy are based on targeting directly and fixing the mind.
Like the theory of the emotional trauma, that is supposed to be an unprocessed negative memory from the past, or the other popular theory as a genetic chemical unbalance in the brain, that can be fixed with medication.
Well as interesting as this two theory's are, they were never scientifically proven, and the success rate of the therapy based on it is miniscule.
Why would your body give you a distress signal as if you were being damaged by an infection or injury but no pain? What part of your body if injured doesn't give any physical pain signals?
It's your nervous system, because it is the job of it to process and localize pain, if you injured it there is nothing to tell you that you sustained damage to it. You would need a nervous system for your nervous system.
Nervous system injuries are pain free and mostly asymptomatic. like in the case of a concussion, nerve imping meet or a spinal cord injury.
The body is pretty well designed, in order to compensate for this your brain and spinal cord are completely incased in bone, but this doesn't make it completely invulnerable you can still get injuries to it.
And when you do there is no way to let you know directly through localized pain, the only way for your body to signal to you that something is wrong is through emotions.