Nicole: I would personally try Nutramigen. Alimentum has Sucrose in it. If your lo has a problem with lactose, then she can also have a problem with sucrose.
There is no lactose in Alimentum. It is replaced with sucrose for the carbohydrate.
Nutramigen is another Hypoallergenic formula. It does not have lactose or sucrose in it. It has corn syrup solids for the carbohydrate.
Like Karen said some little ones cannot handle corn, so the RTF Alimentum work great, but then some can't handle the sucrose, so the Nutramigen works better.
Which soy formula was she on? Similiac Isomil Soy also has sucrose, but Enfamil Prosobee does not.
Not sure if you want to change again, but I would try the Nutramigen.
Good Luck and keep us posted. Wendy