Reaction to a Shot

Question
I brought home a female cat from the animal shelter yesterday.  They gave her a shot of P...., sorry I couldn't spell or say it.  She started running a fever last night and is still running one.  She also has been cool a time or two for a brief period.  I wondered if she had a reaction to the shot?
Other imformation:
She has had a litter of kittens,  some of her milk sacks are very firm but not full.  She has ear mites which I started to treat last night.  And, of course, she is under weight.  Do I need to get a local vet into his office on a sunday?

Answer
Hi Janelle,

take your cat to the vet tomorrow/tonight(especially if she is lethargic) for a post adoption check and to be sure the shelter did not give you any medication that is not going to work, and for some fluids under her skin.

I have no idea what P is so I cant help you there with the shot.