Why do i have chronic heart pains?

i am 16 years old. When i was born, i was born with 2 holes in my heart, but i had open heart surgery when i was 8 1/2 months old, and i went to see a cardiologist until the age of 10, and they told me that i was completely fine, and that i should be fine for the rest of my life, that my heart was completely healed. in the past year though, i have been getting reoccurring heart pains and i dont know why. they come on, and then it hurts to breath. i heard it could be anxiety pains, because i have been under a lot of stress in the past year, but still, it kind of scares me with my history. so please let me know what could be wrong??