If you are in distress, you are in trouble. You're hurting — either physically or mentally.
See the word stress hanging out at the end of distress? There's a good reason for that. The noun distress refers to a state of severe anxiety or strain, often brought about by failing to study for an exam, harassing grizzly bears, or borrowing your sister's clothes without asking. When used as a verb, to distress means to cause all that pain, suffering and anxiety — in other words, to stress somebody out.