Just to be clear everyone, as I've stated above:
My little Muffin does see the Vet at least once a week, and sometimes twice a week. My Vet is wonderful, saved her life. She is a DVM and a holistic practitioner. She has said her heart is good, so no problem there I think. I'm just so puzzled. She is very overweight from the medicine she is taking at this time, (hope to have her off of it soon), and she was a little plump to begin with before she became ill. Do you think it could be her weight?