Back dating a review appeal decision

Hi everyone, does anyone know if I can backdate my appeal for review on a decision to reduce my PIP award made in 2017 when after going for a review assessment and at the same time was going through a very stressful and messy marriage breakdown, and did not have the mental nor physical energy for the fight. The assessor never mentioned during my assessment or questioned me about my usage of a walking stick, which is a suspension type stick with strapping on the handle about my grip or how I handled the stick, but made the observation that I used the aid of the walking stick, therefore, I must have the ability to grip, and due to that I lost about £82 a month of my PIP. I did try to appeal but was knocked back again after I had sent in evidence as to how I controlled the stick without grip and yet could still bear weight upon it using photos and an explanation as to how I do this. Plus I stated that if the assessor had asked me at the time I could have shown her exactly. I did not have the mental strength to fight about it and gave up at this point Now I have just finished with a 2yr nasty divorce and I'm in the process of paying her a considerable amount of money and being forced into taking out a loan to pay her off with, every penny I have is now of utmost importance to me, does any member have any advice as to how to get my PIP award back up to the previous level ? even better if I can get it backdated.
Much appreciate the advice, cheers Moose