I think your doctor has ruled out the chance of heart attack. Besides, it's been 7 months, you've been having increased pain, and doctors didn't find anything in your heart, the chance of clogged artery is small. However, you can still get further tests. How is your cholesterol level? You can also have a CTA to see if any blockage in the artery, CTA is similar to a CT scan, non-invasive and convenient.