I would definitely start with a vet visit to make sure his health is okay and that there is no new pain issue going on because of the declaw. You do know that declaw is not just removal of the claws but actual partial amputation of the toes?...this can often cause a change in gait of the animal which can in turn cause hip joints or knees to go out of whack which in turn causes pain. Your vet will know how to feel and probe to look for pain triggers with the hips, back, knees and even feet.

I would also set up a safe room for your cat to go in when you are going to have company. Why stress him, yourself and your company? I know you love your cat, but you have a right to have company over. He'll be fine in a room by himself for several hours while company is over.

Another thing you could try is Feliway plug-in diffusers.