I've had these symptoms. Sounds like anxiety to me. I also have been daignosed with anxiety when I couldn't pinpoint what on earth was causing it. Sometimes its just there. Things we have going on in life, even good stress (marriage, change of jobs, promotion, etc) can cause anxiety. The sleepless nights, chest tightness, and heartbeat skips are clear symptoms of anxiety. They have several medications that help and also therapy is very helpful. I hope all goes well and please don't worry yourself into anxiety too.