People think heart attacks cause sharp pain.
But actually it is dull pain.
Also from your age and the EKG, it is unlikely you have a heart problem.
According to your description, most likely the chest pain is due to anxiety.
You should take SSRI (selective serotonin reuptake inhibitor) for the anxiety.
It causes the tightening feeling.
What is the knot feeling? Can you explain it ?
Did you have shortness of breath?
You should have a cardicac ultrasound and a stress test (EKG when you walk on the treadmill).
Do any family members have a heart problem when they are young?
Did your doctor listen to your heart?
Most likely your symptoms are due to anxiety.
You don't need to worry about it very much.
You are welcome.
Are you satisfied with my answer?
You are welcome. Take care.