New 11 week old kitten

Hi. We recently adopted a 11 week old male kitten and the first 48hrs with him, he was very loving and lively. He would love to play and was very vocal and spent a lot of time purring and bunting us. We had no issues with him wanting to eat or drink within that time or use the litter tray. Things have taken a turn though since yesterday morning. Outside of having to get used to our other 2 cats and 1 dog, all he has done is sleep. He has been eating wet food and biscuits and still uses the litter tray, but we have been having to encourage him to do so. He has lost interest in being social and won't even consider playing. We thought he had snapped out of it this morning when he was quite vocal to us but has still proceeded to sleep most of the day. We're unsure if this is natural or something else is probably going on. Any thoughts would be great. Thank you

Hello - this doesn't sound like normal kittenish behaviour so we strongly reccommend a trip to the vet.   I wonder whether might have a high temperature, for example.  If your kitten isn't eating or drinking then they can get quickly dehydrated in this weather (UK) so it's worth calling your vet to have the situation triaged (ie to decide how urgently you need to be seen).