Good Morning and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
I am so sorry to hear about your situation....I know this is frustrating for you...
The best thing you can do is to first purchase a DAP Collar which is a canine pheromone that acts as a calming agent and will help Roxy past this. Next, take Roxy back to a good obedience school so she understands that you are the "Alpha Dog" and will listen to you.
Do not allow Roxy off the lead until you know you have total control over her.
I would also recommend that you have your vet examine her and run lab work to be sure that there is not a medical cause for this such as thyroid issues or other metabolic problems that could contribute to this bad behavior. Liver diseasecan cause serious neurologic problems such as you have described.
Don't give up...there are ways to resolve this and sometimes medication can help.
Does that make sense to you?
Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please REPLY so I can clarify for you.
Sincerely, XXXXX XXXXX