Tony gave some good advice.
I've overcome my SA, so i'm highly confident in myself these days but have the odd relapse when major changes go on in my life.
I had a panic attack literally the other day so can give some good advice.
I've been training a team of people on tasks and projects i was involved with, involved in lots of meetings etc and was then being trained on a new job by some guy. Several days into the training i had a panic attack, totally overwhelmed by all the information and pressure. I was shaking, everything became blurry, i never expected it. So i had to tell the guy i wasn't feeling well and that he needed to take over. Things then settled after i excused myself for lunch.
Years ago i used to have panic attacks all the time but overcame my SA and have been living a far more inspiring life. The advice i used to give people all the time is actually quite powerful and is what i'm doing right now. It's based on not concealing anxiety (which is what most people with SA exert so much energy doing) they fear others seeing them with anxiety.
It's probably best not to imagine having further attacks since this usually creates them. So you have the option of concealing it, in fear of having one, OR you out it completly. What this means is that decide to tell people about it.
This can present further anxiety though depending on the situation, as you may become anxious about what people think about you etc. But this option does have it's benefits making people aware and so on. But i've found that what can work best is that you tell people without telling them:
You visualise/imagine telling them about it and your mind realises that they know, that it's alright for them to know and it's ok that you can have anxiety around these people. You see it clearly and they know. When in your mind it's ok for you to have anxiety around other people and not be embarrassed by it, it actually lessens. The energy in hiding it causes a lot of panic. "oh i cant be seen like this"
So you can choose to tell others directly or in your imagination, both methods work.
I've tried both methods and they work equally well, they both have benefits and disadvantages.
Telling others depends on who they are, if it's people you dont really know i'd say just let them know but if it's people you work with or need to remain some distance from then i'd just imagine telling them.
As for telling people in the middle of it, i've used excuses before like i was needing sugar and my body was having a reaction but if it does happen you don't have to say anything, you can just excuse yourself or you can bite the bullet and say you are having a panic attack or you are on medication and its making you feel unwell. Whatever makes you feel more comfortable, forget about the uncomfortable faces looking at you, they're doing fine.
Anyway, hope it goes well.
Aron