“How can I calm my anxiety fast?”

The problem you mention is one that I often had myself. Over time, I found several things helped. One was to become aware of my breathing and my body and keep returning to those awarenesses. Another was to imagine, ahead of time, that I was sitting across from just one or two people who were interested in what I had to say and then to be clear about the most important things I wanted to say to them. I find it is important to switch from the wish to give "a good presentation" to the feeling that I have something really important to say and these people need to hear it. During the actual presentation I like to pick certain people out of the audience and imagine that I am speaking directly to them. It can help to write out exactly what you are going to say and then rehearse it. What you will likely find is that, as you rehearse you will find places where you become more spontaneous and less dependent on a fixed text. Any time that you can also inject humor into the subject, it will help you to be more spontaneous. Eventually you will be able to leave the fear of being judged and realize that you have something valuable that your audience needs to hear from you.

Breathing techniques and relaxation exercises with medications can help with anxiety.

Presentation anxiety? The mediication I have used for this is propranolol. It was successful with a lawyer presenting a case, a musician with a solo, and a presentation. It should be taken two hours before the presentation. The question is the dose. It is a low dose of 10 or 20 mg. The only possible adverse effect is being dizzy from low blood pressure, but this has not occurred with the low dose so far. In advance, take each dose and see your response. If no problem with 20, take 20; if adverse effect at 20, use 10. A 20 mg. tablet can be broken in half. Jack L. Underwood, M.D.

Yoga, breathing in five, hold five, then out trough pursed lips. Sounds like you don't have time to get to a doctor. If you never had asthma, ask for a beta blocker.