That's what you call post-traumatic stress disorder. One would logically think that the anxiety and stress would manifest itself at the actual time that you are stressed, but it doesn't really work that way. Your body bottles up those feelings because it is necessary for you not to break down in order to deal with the stressful situations you are in. But eventually, that stress has to come out, it can't stay cooped up in there forever. And, usually once things are back on track, the anxiety explodes. The timing of this confuses many people, but if you think about it is the normal course of action a healthy human body takes.