ok, try to relax.
She will be ok. LP - IMO should be done by an Certified Ortho Specialist. Our little ones have such little tiny legs, and once opened up you will need an expert (Ortho Specialist) in case any 'creative or artist' work needs to be done. After care is important and must be taken seriously, she'll need to be contained and limited for at least 8 weeks.
She probably has a staph infection (not as bad as you think, ok) - but this can happen as a result of the scratching, thus allowing bacteria into the area. You should wait until the infection has cleared before you do any type of surgery. Clavamox is for the infection. Just becareful b/c she can have a reaction to it. Roxy was on the same thing - for the same thing and on day 8 she had massive diarrhea. At that point, I should have stopped the antibs, but I didn't know that I could, I thought I had to finish until day 10. Well, big mistake, she had diarrhea for 2 WEEKS
The Hydroxyzine is an antihistamine, but this takes a while to build up in her system to work, so don't expect instance results.
All in all - she will be ok. I have gone through ALL of this - including the LP -
So if you want my phone # to talk about it, PM me