Hi Inneedofhelp
Welcome to the forum.
You might want to have a look at the following FAQ which explains where everything is;
www.benefitsandwork.co.uk/guides-for-claimants/faq/forum.
You cannot ask for a second review, the next stage would be to appeal the decision.
If there is a change of circumstances since your son was last assessed then you will need to make a new claim, we would advise you to seek help from your local Welfare Rights Organisation
advicelocal.uk where they can take all your circumstances into consideration when giving you advice.
Gary