Thank you so much for your thorough reply! The vet did a careful exam and found nothing broken but did find that she was running a fever and limping. Her blood work was normal. We believe she has feline calcivirus and she was treated with sub-Q fluids, antibiotics (in case there is a secondary infection) and pain medication (anti-inflammatory). I am also giving her lysine drops. She seems to be feeling slightly better- her fever was gone by the time she was done at the vet's today- but she still is very lethargic. The good thing is that she ended up eating and drinking more (and using her litter box) so it is a small but welcome improvement. Hopefully the outcome for a kitten her age is good with calcivirus?
Limping is not normal for a kitten, of course.
It could be caused by a traumatic injury: getting her leg or arm caught in something and causing a sprain, strain, fracture, or subluxation. This could be painful and she may not want to eat or drink due to the pain.
A second possibility is that she could have ingested a toxin and that is causing neurological symptoms including wobbliness that seems like a limp?
An additional possibility is a reaction to a medication placed on topically, such as a flea or tick preventative. Some cats are sensitive to some tropicals. So if you did place a topical flea and tick product on her just before the symptoms occurred that may be the cause.
I really hope that you have good luck at the Vets!