Anxiety or chronic fatigue syndrome. Had a bad panic attack 3weeks ago. Lately no interest in anything. Lack energy. Feel weak. Headaches.

Anxiety? From the symptoms description you gave, it sounds like you might have both. Please consult your primary care physician.
Anxiety. You may be suffering from depression or anxiety or both. Panic attacks are caused by misperceiving situations and people you encounter. Try to focus on the facts and the objective truth in each situation. Consult with a mental health professional who can help you distinguish between these disorders and will help with a plan so you can return to a health life. Check out antianxiety app.
Panic attacks. You need help so see your doctor or have him refer you to a psychiatrist or psychotherapist.