My cat has somthing badly wrong and i need to know what but i cant get in contact with my vet Please Help!!!!?

Our family cat Pookie is about 4 years old and has always been an indoor cat. About 3 weeks ago she went to a normal check up at the vet where she was given her rabies, feline leukemia, and respiratory desease vaccinations that she has always received as shots before, only the vet gave her a needle-free vaccine that she has never had before for one of them(i don't know for sure which one, but i think it may have been the feline leukemia vaccine). She was perfectly fine for about week after the vet trip and the vet said she was in perfect health, but for about the past two weeks now she has been limping on all 4 of her legs, she has not done much but lay on the couch and when she does walk she wont often get far before she lays down. She has been extra sensitive and her skin ripples at even the slightest touch. She meows in pain when we move and was meowing and hissing for awhile when she walked but she has not meowed or hissed while she is walking for a couple days now that we have heard. We move her to her food and water every now and then during the day, because she has not been going to them much that we have seen and she has not had the appetite to eat as much as she usually eats in a day, but she has been drinking a whole lot more water than usual. She used to always get up in high places, but she has not gotten any higher up than the seat of a chair for awhile. I have researched her symptoms online but have yet to find anything that she could have wrong that matches all of her symptoms. I have found disorders and possible injuries that list some of her symptoms, but all of them so far have also listed symptoms that are completely opposite of hers. I have no idea if could she have hurt herself somehow, if its possible that she is having some kind of delayed reaction to the needle-free vaccines, or if something else is wrong with her. She seems to be getting a little better each day and we are taking her to the vet ASAP, but in the mean time if you know anything about what could be wrong with her your input would be highly appreciated.