Why does everybody say socialize from a young age? I know plenty of pups - especially bully breeds who have been socialized at the recommended age and still come out aggressive.
Please seek professional help for your dog. Not being able to walk it will be causing further problems, the poor thing will be suffering from little mental and physical stimulation. Perhaps try putting it in the car and looking for an off-lead fenced area that is empty so at least it can have some sort of excercise.