Call your vet's office. There are some really good people here, but you need to ask your vet about possibly serious medical issues.
@MrsCunningham............What is clothespin? Im not familiar.
Lethargic pets need a vet visit, it could be anything, and is best not to wait it out.
They are called pegs in the UK too!Aussies, making words shorter since the arvo of 1788.