Chin with heart disease

Hi my name is Nancy and I have a chinnie that has congestive heart disease, He is currently on Lasik, enapril, metcam, probac and a mixture of COQ10, radish, celery and asparagus. He is in with oxygen and a diffuser with mint. He also has had steroid shots which had helped. He has always been a very small chin and underweight. He has always been sickly and is only 6 years old. I also know he was inbreed, but still wanted to try to help him. His breathing is worse and eats very little and is losing weight, so very worried as he is already underweight, I am going to try to syringe feed him, I did not want to stress him, but I have no choice. His vet has run out of options, so hoping someone might be able to offer some suggestions.

Thank you
Nancy