I am so sorry to hear what you are going thru. It seems like she has quite a few things going on. My first beagle had a huge lump at the base of his tail and my vet also said that he would have to remove the tail if it got worse. The labored breathing sounds like it may be her heart really bad teeth can add extra problems to an already aged heart. What does the new vet think about euthanasia? They are usually very honest if they think it is time.