Hi - I would change Vet's if you don't like him/her/them. It sounds to me as though your kitty (ruling out illness, such as UTI, with the Vet) - I would suggest that he is maturing and his hormones are kicking in. Have you tried playing with him a bit more? Some cats are not affection as they get older and outgrow their kittenhood. If you elect to stay with this Vet, and plan to have the cat fixed within the next few days, I would mention your thoughts to the Vet and have him check the cat for illness.

Good luck. Cats can be a real mystery!