sick as a dog/weak as a kitten

I have had acute bronchitis for three weeks, and am taking antibiotic and anti-coughing pills. I feel better in my lungs (no more asthma) and do';t have those terrible coughing fits, but I am "weak as a kitten"--I walk the dog and feel like I hiked the Appalachian trial.

I guess "sick as a dog" describes the utter giving up of a sick dog. When he's sick, my dog has so little energy he doesn't even lift his head when we open the closet door to the sacred treats (plastic-y "beef jerkies" from DM). He just lies there, indifferent to the world.

I am finally able to imagine that some day I'll feel like myself again, with normal levels of energy. But I still feel a bit like a helpless animal, resigned to weakness and not caring about the rest of the world.