I have problems with anxiety too, anon. my therapist wants me to keep an "anxiety journal" which maintains the following:
1. when the attack started
2. what i was doing at the time of the attack
3. what i was thinking about at the time of the attack
4. any other possible triggers
5. what did the attack feel like
6. what was the duration of the attack
7. what did i do during the attack
8. how did the attack resolve
9. what did i do immediately after the attack
but i could tell you that it comes and goes without reason and cannot be grappled with intellectually. he would have been able to tell you this too, if she had been listening to me at all.