--is also that it's the Lyrica--weight gain is a well-known side effect of the med, both through fluid retention mechanisms and through the tendency to make one carb-crave.

Many have sort of accepted the trade-off of weight gain given the effectiveness of Lyrica for them, but in your case I know having that additional weight is certainly a problem for your weakened bones. Unfortunately, most of the anti-epileptics, with the notable exception of Topomax tend to have this side effect. As Dan says, you may just have to experiment with other combos to find an acceptable balance of pain relief/side effects.