Hi Sharon
You don't have to fill in a large form, for a change of circumstances. You can just submit a letter with your additional evidence and ask them to look at it. Try and link your comments to the specific PIP questions so they can follow what you're saying. You can put things together. So for example if you have mobility problems you could link it to preparing meals, washing and bathing and going out - all in one go - so you don't have to do too much explaining.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems