Long medical story. His sensation back?

Hey doctor ! My father is 53 yrs old . He has a long medical story . To begin with , in may 2012 he suffered from back pain followed by a slip disc further followed by a spinal operation done by a neurologist in october 2012 in which he lost his foot sensation as well as hips and urinary sensation . After that he suffers from aggressive pricking pain in his that foot only ( which occurs once in 2 months ) . Once , while he was suffering from this , we applied volini and after that we put hot water pad on that foot due to which a portion of his foot got burnt and he had an operation for that . But he still suffers from that pricking pain from time to time ( which is paresthesia according to what I read online ) . He also had MRI of his foot but it had nothing in it. He also suffers from diabetes and is also overweight . What should we do to get his sensation back?