Marcos I read that you had nerve damage and it affected your calf. I have the same problem and my inner calf/ gastrock has shrunk drastically on one leg. Its been that way for a year and I think its do to my back problems. Have you found a cure? I have know idea what to do?
I have the same problem, except is the outer head of the gastroc. I've got function and feeling back in the whole leg with the exception of that part-well, I have feeling, just not function. Cramps like a mother if I try and flex it and my soleus get's tighter than all get out if I do anything 'back risky.' The best thing I've found so far is to do an exercise for every funtction of the spinal erectors, glutes, and core. Planks, side planks, quadriped, trunk rotations, hip raises, hip rolls, crunches/full sit ups, lateral walks, hip flexor work, internal/exteral hip rotation...etc.
The ones that helped me the most(because they were the ones I ignored the most) were the side planks and the trunk rotations, which are mostly thought of as oblique movements but whose secondary mover and stabilizer are the spinal erectors.