randomized selection followed by randomized selection

I have 8 blocks of questions. I use randomizer to select one of those 8 to present to the respondent. Following that block I want to ask if the respondent is willing to complete another block of questions. If they say no, them the survey ends. If they say yes, I want to present another one of the 8 blocks insuring that they are not presented with the same block fro the first randomizer.