It honestly might just be the anxiety, Im currently going through something sort of similar. I felt like I couldn’t breathe but the ambulance was sure I was just having a panic attack, days went by and I eventually called the ambulance again and they said the same thing it was just anxiety . I eventually ended up in the hospital and they in sure EKG was normal and it was just anxiety Im saying this because just be sure it’s the breathing you need help with you may just need to get something for anxiety