Breathing/heart problem?

[Vbbbh]

So I'm really confused about this one I'll be honest. About 3 nights ago I started getting this feeling that my heart is like skipping a beat every once in a while, the first night it only happened once or twice, then the night after that it starts happening a lot more frequently, like once every 30 30 minutes or so (but by no means exactly 30 minutes, it's completely random) and it was freaking me out pretty bad that night, it was causing me to shake and I had one of the only legit panic attacks I've had in my life, because I honestly thought my heart was going out on me and I was feeling it slowly stopping, this feeling are like I'm short of breath and my heart is struggling to beat, if only for less than a second. But the ones that actually freak me out are when there are 2 or 3 of them back to back. So I go to work the next day and I start feeling some pain in my chest (only off to one side though) and it was getting worse throughout the day, so that's when I decided I needed to go to the ER. So I did. Come to find out, my heart is totally fine, nothing wrong with my blood pressure, I mean they took xrays of my chest, hooked me up to an iv, and did some other tests and stuff. In the end they tell me that it's just chest pain caused by something like a rib or a muscle, but it's not my heart. I'm like "cool", I go home, go to sleep just fine and live my day like normal, no pain and no weird heart beating. Until tonight, I start to get those feelings again, granted it's not as bad because I'm not having a panic attack because I know my heart isn't going out on me, but honestly I was just brainstorming any possibilities as to what it could be at all, so I thought "maybe it's my sinuses that always close up at night and I'm not getting enough oxygen?" So I get a fan and point it near my face where I'm laying down (air circulation and what not, I honestly don't know what I'm doing) but then it starts getting extremely bad at that point, constantly getting that feeling, it freaks me out on a whole other level, so I jump out of bed, in shock and go to lay down in another room... and that's where I'm at now, it's still happening every 5-10 minutes at this point and I'm at a loss. They said my heart is fine, and whatever I did agitated it very badly. The best way I can describe it is as if my heart gas decided to stop working, but only for a fraction of a second, it doesn't hurt, just feels extreeeemly uncomfortable and it concerns me to no end that it's going to happen one of these times and it's going to hurt me or just.. keep happening.. I don't know, I'm scared and also very perplexed as to what is happening to me and I would love to know if anyone has even the slightest of a clue as to what is going on