So I've gotten the basic search to work:
{=INDEX('Combined Data'!$A$2:$C$1000000,SMALL(IF('Combined Data'!$B$2:$B$1000000=$B5,ROW('Combined Data'!$B$2:$B$1000000)),ROW(1:1))-1,3)}
Right now, it's looking just at the $B column of the array, and as it's a huge array with up to 30 instances of the...