The tests that were done are very accurate but they only apply to the day when they were performed. It doesn't sound like your symptoms are heart related at all. It is more likely they you pulled one of the intercostal muscles and that's what's causing your symptoms. I would recommend taking some ibuprofen to help with the inflammation and with time that should really help you feel better.
Oftentimes, problems of acid reflux can mimic the symptoms of a heart attack. That is why your primary care doctor prescribed Prilosec, which is an acid reflux medication. You should also, reduce your intake of food and drink which causes an excess of acid in your stomach...coffee, coca cola, tea, spicy foods, etc. Obviously, the ER doctor and your primary doctor have found nothing to indicate any cardiac problems...so don't worry. The "soreness" in your chest is most likely, muscular, or what is referred to as "costochrondritis" which is an inflammationof the cartilage of your ribs and can occur from any type of physical activity or exertion. Take Motrin for this type of chest pain.