maybe something like this

 
# open file as usual
# foreach line of the file
  # DON'T CHOMP, (still)
  if (/\(/) {  
    # I have found a "(", this must be a title, so I:
    chomp;
    push @titles, $_;

  # now this is the more problematic part cause you need 
  # to extend your search to several lines
  # but you are processing line by line, the idea is that
  # we have a title, now we stop and parse text.

  # 1- pick up all between ) and ( and save this to a $var 
  # ie: with \).*?\( 
  # unfinished yet, take a look to substr

  # 2 -split the different items in this text-block    
      @texts = split /\n/, $var;
      pop @texts   # the last value is the next title, 
                   # so we can discard it safely
      # we enter a inner loop for all items in the array
      while (@texts) {print $titles[-1] . '; '. $_}
 
   } else {    
          next  # this is not a title, whe forget this line
  }  # end of the if-else block
} # end of the foreach-block
[download]

This code is not complete, only a rough draft showing the idea: you have two problems here, 1) - chase the titles one by one (this should be very easy) and 2) - to enter a "inner parse mode" after a title was found, stop the hunting and process all text until the next title line"

Update: you need to wide the @texts array after each foreach pass, so insert a @texts = (); line just after # DON'T CHOMP