Hello and welcome to HealingWell. Congratulations on the new baby which makes me wonder if you are getting enough sleep? The little ones seem to like the middle of the night for their play time.
I am also wondering if you may be having anxiety attacks which are causing your sx? I am not a Dr. however, your tests seem to be OK.
Worry about chest pain and possible heart/breathing problem maybe driving your anxiety, which in turns drives the chest pain and heart/breathing problem. Vicious cycle, it is.
The next time you start to feel anxious, SOB or worrying about your heart you may want to try the following:
Find a place where it's quiet.
Sit in a straight back chair with both feet on the floor or lie on the floor with a straight spine.
Begin inhaling by expanding the abdomen (let it inflate like a balloon), then move the breath into your rib cage and, finally, all the way into your upper chest.
Exhale by reversing this action; begin at your collarbones and exhale down through your rib cage and into your abdomen. Contract your abdominal muscles as you finish exhaling.
You might find it helpful to lightly place your right hand on your abdomen and your left hand on your rib cage to help direct the breath on its journey.
Begin by practicing for one minute and then gradually lengthen the practice to five minutes.
This technique helps to eliminate shallow chest breathing and encourages full exhalation and inhalation.
I wish you peace,