My name is Martin, I may not know exactly what your experiencing but I can tell you my story.
A couple of years ago I had pericarditis not sure if I spelled it right but it means fluid fills the sac that your heart is in.
This causes pressure on your heart and you can't breathe. If you ever get vomiting or you can't walk far before passing out you need to go to the ER immediately.
They should use that gel and press the machine over your chest to get an x-ray where they could see fluid. This is sometimes difficult to do and really have to press hard onto your chest to see in the x-ray.
If there is fluid you go to surgery to cut a opening in your pericardiam so it drains and they can vacuum the fluid out.
From there the Dr's say it should drain automatically if it happens again.
Some signs to look out for are sharp pains in your back or shoulders especially if you lie down crouching normally breaks the episodes. Also and very important is if your jugular vein in your next hardens and is protruding and prominent then that also a strong sign.
I'd be very cautious if you start vomiting and can't walk as these are the final signs. It took me approx a week for my aching and sharp pains to develop a full blown attack. I'm not sure but maybe your experiencing this at a slower rate.
I'd keep getting your Dr to x Ray your heart to check for this and check yourself for these symptoms. You'll now if it gets really bad because basically your heart stops under the pressure.
This obviously isn't the best news to have but I can only tell you the symptoms I had. Have a plan and with most of these events you have a few hours to get to the ER.
Good luck and hopefully your Dr can diagnose this or find what is happening to your heart soon.