Did you completely stop your Celexa and Ativan treatment? I know how easily you can make yourself think you’re feeling better and that treatment is working when in fact you were only feeling better because Ativan helped you to calm yourself. If you’re not using it anymore, and you are now thinking you’re suffering from Sinus Arrhythmia – I’m afraid that the best thing you can do for yourself is to visit your doctor again and see to get a new appointment.
Panic attacks and anxiety that are affecting you and your whole life this much, the only thing you can do, really, is to try to get the treatment for these disorders first. As long as anxiety keeps you doubting your heart is beating correctly, it’s doubtful that you’d get more than temporary relief from ECG or similar cardio test. Your fears would most likely just re-focus to some other part of your body.
Wish you the best,