identity crisis

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A psychosocial state or condition of disorientation and role confusion occurring especially in adolescents as a result of conflicting internal and external experiences, pressures, and expectations and often producing acute anxiety.
• noun An analogous state of confusion occurring in a social structure, such as an institution or a corporation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun psychology A crisis of personal identity as defined by Erik Erikson.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun distress and disorientation (especially in adolescence) resulting from conflicting pressures and uncertainty about one's self and one's role in society