I'll start off by saying this is going to be a long post - but I just need
help and I'm not sure what to do.

I have 2 Tonkinese - they are 1/2 brothers and 5 years old.  My one boy has
always had very smelly breath.  But I had taken him in for teeth cleanings
and the cat dentist never said much to me about it (the did pull a tooth or
two).

This major problem began March 05.  I was on a 2 week vacation and my 2 cats
stayed back with my roommate.  My cat (the smelly breath one) must have
gotten depressed without me (he's quite attached) and he pretty much spent
the whole time sleeping on my bed.  Apparantly my roommate didn't think this
was weird -so she didn't make any effort to spend any time wth him.  
When I got back I notice 2 wounds on the back of the base of his tail.  The
didn't look like tramatic wounds (like a door shutting on him) and when I
asked my roommate how they happened - she hadn't even noticed them.  They
were about a quarter in size and bloody.  Later I noticed my cat chewing on
himself there.

I thought they'd get better now that I was home - but they got worse.  So I
took him to the vet.  He got a shot to make his wound not itchy, some
ointment for me to put on the scabs, and an e-collar to stop him from chewing
on himself right after I put the ointment on.  They also took a biopsy of the
skin (it came back positive for a minor infection - but they couldn't tell if
it was a primary or secondary - especially because of the location of the
wound on the bottom of the tail near the butt).

My cat ended up having to wear the e-collar 24 hours a day because any time
it wasn't on - he was chewing his skin off.  He hated the e-collar.  Then he
figured out how to contort his body so as to scrape the edge of the e-collar
on himself and scrape off fur and skin.  I tried wrapping his tail in a
bandage - but he chewed that off in 1/2 hour.   The only time he wouldn't
chew was when I was holding him.

I took him to the vet again.  They gave me antibiotics to give him 2 times a
day.

About then I moved -- I had been living in Mississippi and I moved to Idaho.
By the time I got to Idaho my cat had chewed all the fur off of his feet and
toes.   He wasn't chewing past the skin - so that was good (I guess).  Then
he was not getting any worse for about 1 month when all of a sudden he began
chwing on his back (by his tail).  He chewed all the fur off and started
working on the skin.  

Also, I noticed that he was drooling and had sticky saliva.  And he had
crusties all over his fur and all over his tail especially.  

I took him to a cat specialist vet here in Idaho.  They were excellent
(although expensive) and the vet looked in his mouth first thing and said it
was the worst case of gingavitis she'd EVER seen.  He was immediatly put on
antibiotics and scheduled for dental surgery.  He was tested for cancer and
FHIV too -- just because he was so sick at such a young age.  He came back
Negative.  Also good on Kidney function.

He was taken in for dental surgery where all but a few of his teeth were
removed.  He also got some Frontline just to kill any bug that might possibly
be biting him.  

The vet figured that once he healed from the surgery and was eating again (I
feed him several times a day with wet cat food to get his weight back up)
then he'd start doing a lot better because he was in such pain.

About 1 mo after surgery he did seem to be doing better - eating a lot - and
his back is starting to heal up.  But he was still chewing on himself -
crusties all over his tail and no fur on his feet.  So the vet gave me some
pills (I forget the name) and said they would hopefully mellow him out - so
that he'd stop chewing long enough to heal and then he wouldn't have the urge.

The vet said 1/2 pill every 12 hours -- but that is too much for my cat - he
gets crazy - running around and bumping into things and howling.  So I bumped
the meds down to 1/4 pill every 12 hrs -- which he seemed to tolorate much
better - but then developed diareaha so now I'm down to 1/4 pill every 24
hours.  Unfortuntatly I'm not seeing any results.  He seems lethargic
(possibly a side effect from the pill) and also his skin seems painful.  He
doesn't try to sit on my lap any more and he is basically just a shell of a
cat.  Plus - he's crusty and I feel bad because I am not holding him as much
because he's kind of gross.  Which makes me a bad pet owner - and I really
love him -- but I don't know what do do anymore.  

Has anyone experienced something like this?  any ideas??