Kelly,
I'm so sorry to hear about your pony. My faithful friend and partner of 17 years lost a bout with founder this past spring. He was only on pasture, but with the large amount of rain that we had pushed the grass up quick, and he foundered before I could even see that there was grass out there for him to eat. He wasn't overweight, nor did he exhibit the typical crestiness that alot of founder cases show.
In any case, research, vets and farriers that I used all suggested that there was a move towards warm water soaks to increase the circulation in the feet, as its the lack of circulation that causes the laminar tissue to die. Apparently the carbohydrate overload causes the tissue to shunt off circulation to the feet and its that lack of circulation that causes blood loss to the laminar tissue which inevitably causes it to die and the result is the coffin bone rotation. Each founder case is apparently unique depending on factors such as how much feed or carbohydrates were ingested and how each horse individually reacts to that overload. Each horses' founder cycle will differ as to the severity and its ability to overcome the inflamation and subsequent tissue death. My poor guy's cycle took about 6 weeks before the laminar tissue death caused massive abcesses in his left foot which caused him to put weight on his right which was too much for the remaining laminar tissue to support and his coffin bone ended up sinking through his sole. Corrective shoing is also standard treatment for founder cases. Heartbars are most common, but there are new trends towards using a 4pt trimming method, shoing and a polymer padding used to not only support the frog (and coffin bone that resides just above it), but the entire sole resulting in the weight being distributed over the entire foot.
All in all, its a tough, horrible condition, and my heart goes out to anyone who has had to witness the extreme pain these horses go through. I say Bute the heck out of her until you can get the founder under control. No one or nothing should have to endure that kind of pain with out some way to alieviate it. Keep in mind that Bute is a temporary fix, and all effort should go into getting her sound and pain free through corrective shoing, feed/hay management, and what exercise she will tolerate without pushing her. Soft, soft bedding is a must as these horses will take to laying down alot to aleviate the pain in their feet and will get "bed sores" from staying down as much as they do.
Best of luck to you Kelly. Keep us posted!