These kittens are very young and lethargic behavior is not normal. These guys should all be receiving regular vaccines at this age and have visited the vet to make sure they do not have any outstanding health problems. The limping and lethargy could be a sign of Felice Calicivirus, or FCV. It is possible that symptoms will resolve themselves in 2 or 3 days but if the decline continues you will definitely want to take them to a vet. www.fabcats.org
