Found fit to work

Hi I'm a newbie on here, I have worked and been self employed much of my life, never claimed a thing from the state, I have had a progressive back complaint for about seven years, with severe degeneration of two lumber disks, I live on pain killers and sleeping tablets and have been forced to cease work for the last two years, I never claimed as I had private insurance that covered me for 24 months, this has now expired, I have seen specialists for my back and am on the list for surgery next year as there is a outside chance of paralysis, it's also caused an uncontrollable bowel disorder, so life is dismal for now, I am due to retire when i'm 65 next April, I had two assessments for ESA, one for each disorder, both by junior doctors, because I never went in there screaming and holding a walking stick I have been found fit for work, I have applied for PIP instead, and was seen by a nurse, I have no faith in this system, how can these unqualified individuals over-ride the evidence of a Neurologist and Gastroenterologist