Anxiety nips at my heels everyday.  Anxiety attacks viciously, sometimes without warning.  What to expect:
I found a quick description at http://stressesanddresses.com/2014/10/07/5-tips-for-anxious-minds-panic-attacks/ plus some tips to help with the an anxiety attack.

A quick search brought up some interesting links…as always I present these links as a starting point for my own research, I haven’t read everything.  I do try to select those that appear to have healthy information.

http://www.anxietycentre.com/anxiety-symptoms.shtml

Mayo Clinic http://www.mayoclinic.org/diseases-conditions/anxiety/basics/symptoms/con-20026282

WebMed http://www.webmd.com/anxiety-panic/guide/anxiety-panic-guide-symptoms-types

HelpGuide.org http://www.helpguide.org/articles/anxiety/anxiety-attacks-and-anxiety-disorders.htm

This is a starting point.  I recommend Anxiety Symptoms for search words…..pages and pages are written.  I am not alone in the battle of anxiety.  PTSD is in this spectrum of disorders and considered severe.  Great just great (I really need a sarcasm font.)