What Do Severe Heart Palpitations And Fatigue Indicate?

Question: I am a 36 year old male. I have recently been experiencing heart palpitations numerous times per day, every day. It doesn't matter what I'm doing when I get these palpatations. I can be sitting down, lying down, exercising, typing on the computer. I have had these before, but now my heart feels like it's racing, but my pulse is 58. I feel discomfort in my chest, mild feelings of presyncope, and dizziness, tight chest, fatigue, some trouble catching my breath. Also when I have the heart palpitations I experience some pain in my chest, and sometimes it last longer than 5 seconds at one time. I also feel the palpitation in the back of my throat. I had a holter monitor for 5 days and the results were .85% of my heart beats were PAC, and 20 total PVCs. I just had a stress test yesterday (so I haven't sat down with the cardiologist yet), and the person administering it said it looked normal, but when I was cooling down, my heart must have palpitated 50 times and I felt a little dizzy. This concerns me because two years ago I was considered obese, but was able to run for more than 5 miles every day and not feel any heart palpitations, or other symptoms. Now I have lost 43 pounds and am no longer considered obese. I only lost the weight by eating healthier and over 8 months, so no ridiculous dieting. I have also been using a wellness center to help with my weight loss. Now, just sitting causes me to feel these symptoms. I know there is something wrong and I need to find out what this is because it really worrys me.

I just came to the ER now and will ask to do the ECG Blood work and cardiac echo. I am having one of these episodes now. I have only had an EKG, holter, and stress test. I will try to get these reports and upload them but it might be a little while before I can get them. Thank you for letting me know what to ask for.