Any change in routine, you might see some OCD symptoms in cats
. A new person in
the home can also upset cats
into OCD behaviors.
I would try to get some flea preventative-Frontline, Advantage, etc., if you don't already have your cats on these. Change the diet back to the one they liked. And, last, but not least, try to stay in one place(of course, if you can), it'll give Buster more security and happiness, and less obsessive behaviors.