HI Emma
If the dog is showing unusual physical symptoms, such as those you have described, your mum should have a chat with the vet because it could be a tumour or some other neurological problem, and it is possible this may have a bearing on Tansy's behaviour. What you have described is not normal and is certainly a cause for concern

When i say havea chat with the vet, i mean to talk about whether it may be something other than a tumour. It seems shame if she was getting better with the help of a behaviourist and now is slipping back to her old ways because of family upset.
It has been known for dogs to become so stressed that they do react physically, such as for instance, tail chasing and believe it or not, moon walking!!! Yes, really!
If you feel the problem is basically due to family problems maybe the dog could be rehomed wiht a calm older couple or something, but she would need to be assessed.
I am not sure about organsations etc. ..... try lookng in Dogs Today magazine (W H Smiths) for details. Good luck.
Lindsay