Its not that stress hides inside you but it accumulates. Let me use a car analogy. When you buy a new car it runs like a gem. Even without any major mishaps or traumas, you'll notice over several years of wear and tear (which is analogous to stress) that your car doesn't run as well as it did when it was brand new....doors might squeek, hinges feeling loose, just not as solid as it used to be. Stress, much like wear and tear on a car, can be a process that happens over time.
So, when a person accumulates stress and tension the nervous system has to continually adapt. When the stress level gets beyond the point of a person's system being able to adapt then symptoms start to show. Yet, the human body being as amazing as it is...it will adapt and often the symptoms are just transient or short lived. Thus, you will feel as though you're okay because your body has adapted to your level of stress. However, you must understand your stress accumulation has probably not decreased, its just that your body has adjusted/adapted to the new higher level of stress accumulation. Your body may go through several bouts of this adaptation process (thus showing up as recurring acute bouts of your symptoms) before it finally expresses itself as something more severe or the symptom is now chronic and won't go away. It is at this point that your body has no capacity left to adapt.
Most people don't have any tools or strategies to relieve core tension and stress in their bodies. When people feel stress they either suck it up, drown or numb it out (through alcohol, recreation drugs, or over-the-counter and prescription meds). Now, the only real way to get better and feel better is to relieve the accumulated stress.
I'd suggest looking into mind-body based approaches that should help give you those tools and strategies for reduction of accumulated stress and tension in your body.