I went through this with Nevermore, though his stress grooming and extensive hair loss was for different reasons.

He was on the streets for about six months before animal control picked him up by which time his digestive system was a mess and he was really skinny. Then he was stuck in a cage for 3 months, a cage so small that his back nearly touched the top. I was at the tiny adoption place to look at a disabled cat and noticed a large black cat half-rearing up and pounding desperately on the glass door. I saw he had lost a great deal of fur from the same areas as your cat ?name. Of course, I had to adopt him, I couldn't leave him to live like that.

He's been in my home for about five months now and he's still getting well and settling in. His fur has almost grown back fully, I can't feel his backbone as easily, and he no longer has blood in his poop. But, he did need plenty of time in a settled calm environment to get that far on his road to recovery.

Does the new cat annoy your fur loss cat? Does he get less attention now? Do they have separate eating areas? Are there problems with sharing food and water bowls, and litter boxes?

Your cat probably needs time to settle into the changed environment but you could talk to your vet about putting him on Fluoxitine if the over grooming continues. Some cats, like some humans, are more easily stressed out than others.