Randy   it the vet can't figure it out  it maybe time for a new vet.  My
rumble  would do this due to his epilepsy.
You may have to have the cat medicated to came him down but  IMO  try
stopping the other cat from picking on this one it may be causing this
nervous habit in this furball

Hi Randy,

What kind of flea treatment do you use on kitty?  If your vet is treating as
for flea allergy (which is how it sounds), then perhaps you need to reassess
kitty's basic protection.  If a flea has to bite before it's killed, then
that bite is one too many IF kitty is reacting to the bite.  Of course,
kitty could be reacting to the insecticide used.  You will only find this
out by trying different forms of protection.  Perhaps a herbal cure would be
more gentle on her skin?  Could you discuss this with your vet; kitty
needn't be present, so she would not be alarmed.

It is always possible, of course, that kitty has developed an excessive
grooming habit which she no longer needs.  Some cats (quite often skittish
ones, like yours) develop a habit to solve a problem.  The vet solves the
problem (cortizone shot in this case), but the habit persists.  An ex cat of
mine had a similar problem and, once the vet had done her stuff, I used to
sit with puss in the evening and keep her from biting her fur.  After a few
days of this kind of distraction petting, she overcame the problem.  If you
try this, allow kitty an occasional nibble so she's comfortable.  Always be
aware that the biting may be a real necessity (you don't want to be cruel),
but it's worth proving whether or not it's just a habit.

Another possibility is a thyroid problem.  A live-in petshop cat I used to
know had this and she nearly bit all her fur away; she looked a pathetic
mess.  One day I visited and she was well and hugely fluffy and hairy.
After I'd made a great fuss of her, I talked to the petshop owner: kitty had
received treatment from the vet for her thyroid problem.  The difference was
amazing!  Alas, if your kitty has thyroid troubles, you will probably have
to give her a pill a day for the rest of her life.  Because she is so
skittish, I truly hope this isn't the case.

Well, that's my input for now.  Before I sign off, though, I should mention
that a vet has recently joined this group.  You may be lucky and get a
response from him.

Good luck, and love to kitty.
Spider

How long ago did the now 3 year old enter your now 5 year olds life? When
did the excessive grooming start? After the arrival of the younger cat?

If so, perhaps seperating or removing the younger cat is the solution.