Pain under the left shoulder blade is usually a referred pain from abdomen like stomach ulcers, acidity, pancreatitis, or ectopic pregnancy or from the chest like in heart attack, pericarditis, pleuritis, pneumonia, pulmonary embolus, and aortic dissection. Since the pain
is not much chances of chest
related causes are less. It is in all probability acidity due to medications you took.
Raise head end of bed. Take Omeprazole empty stomach in morning and an antacid gel at bedtime.