Hi, I am in a similar situation, I have a presentation coming up in a matter of days... the best path available to you right now is to go to your General practitioner and explain to him/her that you have a transient need for a benzodiazepine... preferably Xanax or Klonopin.
I'm not fretting over my presentation because I know that .5 miligrams (a low dose) of Xanax takes away the intense fear COMPLETELY. I've done three presentations of 5 minute length with no anxiety what-so-ever. Now, obviously these aren't drugs that you want to take for an extended period of time... as they do build dependency and tolerance, but I had a conversation with my GP and they're extremely safe if used responsibly and for a short period of time... I.E. presentation day.
They're tranquilizers that increase the ability for the neurosecretionary cells in your brain to produce the neurotransmitter GABA... which in turn interacts with other neurons in your brain to slow their firing processes down... I.E. the necessary firing rate requisite of starting a panic attack is taken away in the presence of excessive GABA inhibitor. At appropriate doses it's effectively impossible to have a panic attack assuming there's no prior tolerance build up or what have you, within an hour of taking the medicine... so take it like thirty or so minutes before your presentation.
Of course, you shouldn't plan on driving and you shouldn't take alcohol with this drug... as both increase the risk of drastic side-effects.
Outside of this, the other course of treatment is a relatively small paced-long term treatment, which you should focus on.. and that's Cognitive Behavioral therapy... but for now, your best therapeutic course of action is to get ahold of a benzodiazepine...