I don't know if this will help but we can hope....
I get severe leg and arm pain especially during "die-off" (Jarisch-Herxheimer reaction) which is the feeling we get wen the "critters" die because they little darlings leave a poison behind to further plague us. Aside from the flu-like symptoms I get a feeling of acid under my skin, a terrible burning. I recently discovered, on a whim, that drinking warm water with fresh (not warmed) lemon juice in it helps within 15-20 minutes. I was amazed!
I hate to tell you how many narcotics I had taken to relieve this with no effect and yet this simple, good-for-you drink worked. If this is what she is experiencing give it a try. Though lemon juice is an acid it changes in our systems immediately turning our "climate" alkaline, hence the relief.
My Lyme doctor also told me that when I use the Epsom salts baths to put a cup of soda in with the cup of Epsom salts. It worked much more effectively.
My heart goes out to you and yours,