At my wits end with chronic PVCs & other weird symptoms

I am 65 years of age and have experienced irregular heart beats since I was about 12 or 13. Never really bothered me until about 3 mths ago. I am not a smoker but did drink a few triple shots of caffeine from Starbucks every so often. I retired at 63 and then went back to work part time. Very low-stress job that requires a lot of driving. My irregular heart beats are so out of control that I went to emergency wore a halter monitor for 24 hrs, had 2 EKGs, an angiogram to check for blocked arteries, even had an endoscopy due to chronic GERD thinking it was my hiatal hernia. Not only experiencing chronic irregular heart beats but experiencing pain in abdomen and bloating. Had an ultra sound & CAT scan to rule to gall bladder and possibly even a blood clot in lung... nothing showed up. So many symptoms and so many specialists and still no one can figure this out. I am at a loss... tried a beta blocker, anti anxiety med, but so far, no change. I do live and work in the mountains at 4,000 ft, which seems to exacerbate everything. I'm thinking I need oxygen, maybe even perhaps an electrophysiology study (test to check the electrical conduction system of my heart)... hopefully this will help doctors understand the nature of my abnormal heart rhythms... I will try anything at this point. Anyone out there with PVCs and experiencing abdominal pain and bloating??? Thanks for reading my post.