How old are you ? I went through something like that for 3 months, and thought it was chest pain/heart attack kind of stuff... They did a stress test, which was inconclusive, did a heart cath which made the doc think I had a slight mitral valve prolapse, did an E something or other (sonogram of the heart, actually) and was told I was fine. We also did a long variety sugar tolerance test, and while the results weren't horribly low, the reality is that when I eat sugar, my body dumps it into fat cells leaving not so much in my blood stream.
I learned later that these could all be caused by the hormonal stress of menopause kicking in. . . I also read that if I get rid of caffeine, it isn't so bad. So I did that, and it's better. I also make a point (when I'm being "good") to avoid carbs, and that helps, too.
It IS scary stuff, whether it is just life-induced or menopausal . . . When it does happen, I try the early stages of lamaze on myself -- the slow, deep breathing and relaxation stuff, and that gets me through.
BTW, I LOVE the ages of your kids ! Mine stretch from 28 to 14, and I've loved having the "adult" kids while also raising the rest of the brood. :-)
Take care. Try to pinpoint the sources of your anxiety and work on them if you can. If you can find time in the day, do some things for you, take walks, anything that is stress-reducing. :-)