
Hi Weezie,
I've been there and done that (one of mine is a re-home that arrived unsocialised) so you have my empathy and sympathy but also my reassurance that this can be turned around :)
Personally, I have her to the Vet in the first instance for a check-up and to establish that the cause is behavioral rather than a physical/ neurological root cause (for example) Discuss this instance with your Vet and if she has an all clear health wise you can discuss having a referral letter for a behaviorist.
Using an accredited Behaviorist
The Association of Pet Behavior Counsellors has pretty much all the regions of the UK covered.
It
doesn't cost an awful lot, although I see a fair few Charlatans charging in the hundreds. :(

I paid about £22 for an hour session (of which my trainer never looked at her watch and we often had well over the hour) included in that was access to her via the phone anytime we wanted, and an abundance of articles and handouts and homework, and a period of time where she would accompany us on our walks.
3-4 years on she still keeps in touch although we have no need for her, as we now have a dog that for the past 3 years now has consistently behaved calmly and happily :)
Aside from the handling tips you receive the main benefit to me was having an objective pair of eyes with me, that could see things that perhaps I was missing/not seeing during my dogs interaction (with other dogs, with me, with other handlers)
Hope this helps? really believe from personal experience there is no substitute for a good trainer with you :)
Best of luck.