I have to agree w/weaver....its more than likely the afteraffects which since it was your first time, is just something your not used to. After a "long" weekend i could usually feel it for days. Not pain as much as constant panic feeling in my gut and chest.
I wouldnt advise riding that train again though.
IF you are not used to taking cocaine, which makes it easy to drink more than usual, it can take awhile for the body to calm down. Heart issues are the number one killer of stimulant users. Adding a depressant, alcohol, makes it a speed ball, upper and downer together. That is a major killer of many, of which I knew a few. I would go get a general check up, if you haven't in awhile, just to make sure. It's nice to rule out physical illness causing any symptom. I doubt you are having deadly effects from the drugs/booze, but sometimes drugs will intensify underlying issues that have been lurking in hiding. I highly suggest you find other ways to be social and party, just to prevent all the heart ache so many of us went through in our active drug use. If you are not an addict, then for your and those who love you's sake, don't feed the beast that will consume you in the end.