How to cure stess related headaches and indigestion in teenagers?

Psychological assess: I would suggest a psychological assessment; the manner in which your question is posed suggests a somatoform disorder (depression or anxiety expressed as physical symptoms).

Need for release: Stress can indeed wreak havoc on the body, so i would encourage the teen to share what's on her mind, what most matters to her, and what's most upsetting for her. I would also be interested in understanding a little more about what she herself thinks might be going on inside of her. I would also want to remember that sometimes "somatizing" can be an effort to get attention. So give it freely!