Hi Charlotte
If your condition has deteriorated from when you had an assessment, the Tribunal will disregard the change in your condition, they will only assess you as you were when you were assessed.
We cannot advise you what to do, as we do not know what you were like when you had your original assessment.
You need to seek specialist advice from your local Welfare Rights Organisation:
advicelocal.uk where they can take all your circumstances into consideration when giving you advice.
Gary