A couple things
I wouldn’t stop heartworm prevention on the other two, and I would still get rabies vac also. An undamaged liver should not have any trouble processing HW meds. I just wouldn’t add additional challenge to an already damaged liver in an already senior dog.
All the symptoms you are seeing now are completely normal under the circumstances you attributed them to, so of course you couldn’t put 2 and 2 and 2 and 2 and 2 together and get 10, however as a totality of symptoms, it does look quite suspicious.
When are you taking her back for more tests?
