Can you please describe a panic attack and/or general anxiety disorder?

Panic attacks can : Develop rapidly ; include: marked anxiety; rapid, pounding heart beat; chest tightness or pain; shortness of breath with hyperventilation; hot or cold flashes; a sense of butterflies in the stomach, nausea or even vomiting; tingling of mouth or extremities; increased sweating; feeling faint or lightheaded; headache or shaking. There may be difficulty swallowing or tight throat; a sense that you >.