My Cat Has No Will To Eat or Drink and Is Very Weak

Around Christmas my 8 year old persian-tabby cat Amy developed a limp in her
rear right leg, we are not sure what caused it but we believe it was from
trying to jump on top of a high counter. Along with the limp she developed
a certain listlessness. We took her to a vet and he believed it was simply
a soft tissue injury causing her some pain, so we asked him to administer a
shot of painkiller to see if she felt any better to try to elimate any
variables. Under the painkiller most of her limp dissaperared and seemed
alert but once it wore off she became listless and began limping again. The
day after it wore off we took her to the vet to recieve an xray, this xray
gave no results. The vet told us that it is likely a torn ligament and
could heal in a few weeks, he gave her another pain killer and prescribed
some anti-inflamatory drops to relieve the pain. In the following weeks her
appetite has slowly diminished and we have been trying different foods to
try and encourage her (including all the old tricks warm food blah blah
blah), yesterday morning my mother took Amy to a veterinarian who gave her
another shot, prescribed a painkilling medication to bolster the shot's
effects and recommended different foods to try. That afternoon Amy ate
remarkably well, gobbling down food left and right and we gave her a
painkilling pill that night. In the morning she was no longer hungry, in
fact she seemed completely disgusted with food. This afternoon Amy is very
weak, she barely can climb stairs and I am afraid she won't last very much
longer (besides yesterday she barely ate anything on the weekend). Half an
hour ago I had force fed her some water through a plastic dropper and I was
wondering if anyone has any ideas on how I could get some food into her? Or
any other suggestions? I am 14 and my cat was the very first friend I had
and my best friend, I can't imagine my life without her, please respond.
Thank you for reading my post and god bless.