Hi ploppy111: Something that used to work for me - and I still use it once in awhile - is to excuse myself and go to the ladies' room where it is quieter and take a break, a breather - so to speak. I would wash my hands with cold water, let it flow on the inside of my wrists where the pulse spots are all the while using positive self talk. I would also take some deep breaths and get grounded again before going back out. If it was really bad, I gave myself permission to stay a bit longer. No one really noticed and if they did, I would just say I wasn't feeling very well but was getting better and I'd be out in a minute. A glass of water, slowly sipped as I was "resting" helped too. Most restrooms don't have cups so it might be harder for a glass, but maybe you've got bottled water.
One of the reasons the cold water on the wrists works - I read this in a support group I used to go to - is that animals in the wild, after a fight, often go and cool down in the river afterwards, it slows down the heart rate. Another way to cool down is to place a cold towel (paper towel works) at the back of your neck. Worth a try anyway.
How about distraction? When you feel your heart start to race - whatever symptoms you may have - start looking at details around you, such as what colour the walls are. Is there any art work you can look at for distraction. What kind of flooring do they use. If there are refreshments, get a cool drink and sip it, concentrate on the flavour and how it feels going down. Can you stand outside for a little while and come back? Have your drink outside.
One lady I knew used to keep a little rubber ball in her handbag. When she felt the anxiety coming on, she'd squeeze it and that released some of her stress. Is there something you could use that could work for you? Perhaps you could practice it at home before going out. Sort of like a plan of action, just in case.
One designated "safe place" I made for myself was my car. If and when I was out and felt anxious, I could sit in my car for a few minutes until it passed. For me it was "my" car, just like at home, so I felt secure there. I usually brought some water to leave in the car.
Hope some of these tips might be helpful to you.
Sunny