I am sorry to hear of your attack today:( It is really frustrating to think that you in the clear...only to have one pop up, unexpectedly.
This happens to everyone though. Even when taking meds, breakthrough anxiety can happen.
You may not even be up to quite a theraputic level yet, since you are just now going into your 5th week.
I would give it a bit more time if things are going okay other than the random attack today.
No med fully guarantees to completely eliminate attacks...so that is where your coping skills (and possibly a benzodiazapine as AG mentioned) come in!
Here are a bunch of self-help ideas to try. Doing these daily will help to keep overall stress levels low, and reduce the chance for panic to happen.
Self Help sites with breathing/relaxation exercises instructions
Panic attack relief exercises:
Wishing you the best....and keep posting!
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT