My husband I both have had bypass surgeries for this problem due to "Clogged arteries" from eating too much fat and grease for too many years.
I suggest you start taking a 81 MG aspirin ASAP daily? Locate a cadiologist you feel comfortable with and let him explain your present options if needed to you.
At your age, I would be inclined to think it cannot be too serious yet and a lifestyle change, along with watching your fats intake is appropriate. Generally, keeping your blood flowing freely by thinning is a basic step. IE: Aspirin daily!
They can do a exploratory operation and look inside of your heart by going through your groin artery. Real simple, not painful, just a day surgery generally.
Hope this helps? Stay calm, relax and check it out with qualified specialist.