Had to "put our dog down" today. after, i started sobbing, but suddenly couldn't breathe...could only make this heavy gasping sound until i calmed?

Acute Anxiety: Attack. Sorry you lost a member of your family. That all sounds like a fairly normal reaction as your grief took over and you were crying so hard it became hard to breath. It is quite a common reaction to a major loss. A pet is truly a member of the family and you will greave their loss. It is normal and will take time to get over. My condolences.