If you won't go to the hospital now, then you should once you're done with whatever you're doing. Even if its partly panic, we cannot give you the reassurance you need being that we are not medics and cannot do tests on your heart or know enoguh about it.

I cannot find any direct info to stay about the feeling of your heart racing, so I can't advise you using that. But if there is chest pain, weakness, shortness of breath, slurred speech, problems with vision or balance it says you should seek immeadiate help. Obviously if you don't want to right away, then you should at the first opportunity. I know this event is important to you and your son, but your health should come first, if you are unwell it is only going to worry you and everyone around you and risk you becoming worse whilst you are out. That said, it might be panic, but I'd personally rather get checked out than be wondering.