I’m certainly not a doctor but I’ve never heard of anything like your heart/chest pains being caused by wearing a rig, and certainly not one as light as the one you are lifting. I would assume that your issue was not caused by your vest, regardless of how much or how little padding there is in the chest section, or how loose or tight you are wearing it. See a doctor.
Ron and Janice have been operating rigs as long and as well as anyone out there so their advice is valid and well worth considering. I’m not sure what you were looking for as a reply to your question, but your tone in follow-up posts came off as a bit misguided and condescending to those taking time out of their busy schedules to give you guidance. Victor’s advice from yesterday about taking a workshop is also valid if you haven’t already done so. Though I’m quite sure your chest pain wasn’t caused by the rig, learning how to fly the rig as it was intended will prevent all kinds of future injuries, especially if you continue with this physical pursuit for any length of time or eventually move up to a bigger/heavier set-up.
As I mentioned above, the first thing I would do is get to a doctor. Chest pains aren’t anything to take lightly regardless of your age, and the fact that they were still happening several days after your shoot is really scary. I would think that the sooner a doctor sees you after/during an episode like you described, the easier it would be to pinpoint the issue so you knew what you were up against, and how to prevent it going forward. I would assume that the longer you wait to see a cardiologist or similar, the less likely they are to see what you were experiencing. In a profession like steadicam, your health is everything, so you can’t take it lightly. When you make your living on your feet, it can all go away with one misplaced step, so treat your body as though you were a professional athlete and get things checked out when they don’t respond the way they should.
Good luck, and let us know what you hear back from the doctor if appropriate; it might help someone else down the road with a similar issue.