If the pain is under the shoulder blade then it could be due to a problem with the stomach (like acidity, gastric reflux, hiatal hernia) or due to pancreatitis, ectopic pregnancy maybe ruled out in your case) or in the chest like angina or heart attack, pericarditis, pleuritis, pneumonia, pulmonary embolus, aortic dissection.
Yes, gas and
reflux can cause this pain. Take Omeprazole
empty stomach in morning and an antacid gel at bedtime.