The best thing to do you have already done; you've scheduled an appointment for a check. Other than that, I'd recommend trying to calm yourself when you feel anxious, cut out caffein and other stimulants, and exercise deep breathing relaxation mechanisms. Try memorizing scripture about not worrying. Get a full 8 hours of sleep a night. Use positive self talk to lower your stress.
WHEN YOU GET THE ALL CLEAR FROM THE DOCTOR, see a chiropractor about alligning your spine properly and re-seating your ribs properly - they can cause terrible pain like heartattacks when they're not in the right position. Then start a stretching exercise program like Yoga and a strengthening program like Pilates.
Feel better soon!