Did they do any blood work on you? Seems pretty weird one EKG is good, the other is abnormal...not making sense to me, especially since they whisked you away in an ambulance. Were you seen just by the ER Dr. or did a Cardiologist see you? IMO you need a good blood work up to see what is going on, especially since you said your having breathing problems.
Also don't rely on an EKG for a proper diagnoses of any heart problem, as you need to have your Troponin levels checked and a stress test to see if there is anything wrong with the heart. My husband just had slight chest pressure and a bit of shortness of breath when I took him to the ER. They kept him overnight to do a stress test the next day. During the night his Troponin levels went up indicating a problem so they skipped the stress test and did an Angioplasty and found a blocked artery. Dr. told us had we waited another week he would have had a full blown heart attack.
Don't mess around with labored breathing or chest pressure, make an appt. with a Cardio. Dr. and get the right tests done.
Best of wishes...JJ...