I have had this many times before but less since I quit drinking. There is nothing wrong with walking out and helping yourself calm down. Just go back in again afterwards
Don't let it stop you from getting help. Maybe get a good book on panic attacks and try and find something that works for you. I found just trying to reassure myself that I wasn't dying or going to pass out was all I could do in some situations, but friends of mine have used things like EFT to help with panic attacks x