First thing we need to do is get a rectal temp if possible. We need ot be sure she is not running a fever. If her temp is over 103.5 then she needs to be seen right away.
Now cats run a normal temp of 100.5-102.5 so it is not uncommon for their ears to feel hotter to us sometimes. Look in her ears and make sure they are not red as infection could explain the heat and appearing to have lost hearing.
If her hearing and or eyesight have severely diminished then this could account for her crying more then normal causing irritation to the throat and even laryngitis.
The fact that she ate like a bird should have concerned your vet if she was there for 8 days. Cats unlike dogs can not stop eating or decrease their eating for more then 48 hours or this can have a direct effect on the liver. Cats will not stop eating unless they are very sick, in pain or extremely stressed. When they stop eating or decrease the amount of food in take the body begins to burn fat for energy. A cats liver can not process this fat and a condition called hepatic lipidoses develops. This can be fatal if not addressed promptly.
I am concerned that what you are describing with her ankles could be a condition called diabetic neuropathy .This causes the ankles to appear weak and they begin to walk more on the hocks. This is a complication due to untreated diabetes and it is painful Here is a link to more information on this LINK. Diabetes, hyperthyroidism and kidney disease are the 3 most common health problems that we see with senior cats.
Yes it is common for them to have some decrease in eating and drinking due to stress but that does not mean that in a clinic situation we allow it to continue especially to the point of dehydration. There are medications we can give to decrease anxiety and things like SQ fluids and even appetite stimulants. For a cat to decline and nothing to be done while under a vets care is just in my opinion unacceptable.
I would get her in today and get at least baseline blood work done to look at the liver, kidneys, and blood glucose levels, I would also like to see a thyroid test done and if they do a senior blood panel it will be included but I think we need to know where organ function and BG levels are in order to know where to go from here.
I hope this helps give you some direction. Please reply back if you have additional questions and I will be more then happy to continue. If you have no additional questions please take a few moments to provide a rating as this is the only way I am compensated by justanswer for assisting you.Even after rating you can still come back to this thread and there is no charge for follow up. I would like to know what the results are if you can get some blood work done.