I am so glad you finally have a diagnosis and it does seem to fit with her symptoms, including the nosebleeds.
I know with humans, they sometimes have to be on doxy for quite a while to clear up lymes disease, at least a month for suspected cases. Doxy in many people can cause severe tummy upset, so could be causing her to not eat. It should only be given on a full tummy. I know, very difficult to do when she won't eat
.
Sending lots and lots of
Timber's way and hoping that the Doxy will do the trick and get her healthy again