What can I do for my dog?

My 15 year old dog tested positive for heart worm a few months ago. The vet told us we should not treat it due to her age. In the last two days, she has started growling at the other dog we have (one of her puppies), and tonight we noticed her stomach was swollen, she is lethargic, wheezing, and coughing up a lot of phlegm. Is this the end? What can we do for her?