Emotions & mind
Why do i feel anxious about everything?
Anxiety is a real physical state, not a character flaw, and in adolescence the brain's threat-detection system becomes more sensitive just as more is expected of you. Persistent anxiety that affects school, sleep, friendships or eating is worth getting help for, and it responds well to it.
What this does and does not tell you
This is general information, not a diagnosis. Only a clinician can examine you, take your history and run tests. The same symptom has different causes in different people.
If something is sudden, severe, or getting worse quickly, get medical advice rather than reading on.