I am experiencing irregular heartbeat, dizziness (better by: rest) (worsened by: changing head position, after exercise, sitting upright), vomiting and heartburn (gerd). The following also describe me: Nausea, Lightheadedness, Fatigue, Rapid heart rate,

Rapid HR. If you’re having those symptoms along with a persistent rapid and irregular heart beat, then you could be having a significant problem with your heart rhythm. You need to see a Cardiologist, and if you can’t get in to see one today or tomorrow then you should go to the ED. Regardless, the heart rhythm issue needs to be elucidated.
Irregular heartbeat. Go to the Emergency Department as soon as possible and not to an urgent care.