How long does it take to recover from chronic stress disorder built up for 5.5 yrs?does excessive masturbation(5 times a day for 13yrs) make it worse?

Depends: If you are seeking treatment for the chronic stress, it can improve quickly (a few weeks)-with cognitive beavioral therapy possibly in connection with short-term meds depending on the severeity. As for masturbation, it generally relieves stesss not increase it assuming you don't feel guilty about it ; there's no reason to feel guilt since most people do it to some degree.

Impossible to predict: I would recommend that you get into or stay in therapy for your condition. I don't know what type of stress you had so i'm not going to recommend any particular psychotherapy but find a therapist that you are comfortable working with. It is also impossible to predict how long it will take to recover from any stress reaction. One lasting five and half years makes prediction even more difficult. Masturbation would have no effect on any of this.