About two months ago I was at my friends house with a broken ankle. I had taken 2 10mg flexeril at about 11am and 1-2 more at about 7pm. It was around 4 am and I was getting up to get a drink. I've experienced slight lightheadedness upon standing for most of my life but this was different. The room started to spin and my ears muffled out and and I woke up on the floor. Then I got up and blacked out again. I fell asleep shortly after and woke up having some chest pain. It has since slightly decreased and only happens at time but it's produced many palpitations a day, as to where I used to have maybe one every few months. My EKG, echocardiogram, and holder all came back with "normal" results. Would you be able to possibly give an answer or an input. And note I've been super stressed about it