114218 SQL/PHP injection problem

I run an online text based game. It uses php and Sql. I get quite a few people trying to inject the database through input boxes that are within the game. I have had no problems for some time, but recently someone has found a back door/input area which i have abviaoulsy not had covered with strip tage or something. This is a real pain for me since i have had to close down new registrations until i have this fixed. What i need is someone to go through each page of my scripts and look and test for possible loopholes/security risks/exploits etc. I will give full FTP access for you to view the files, this shouldnt take too long if you are using a script to find where the input boxes are. A generall overview will also be needed for anything that you may see that may need some extra work on. I need the programmer to be on MSN or Skype chat so i can help interact if i am needed. I am based in the UK