I think there has to be a Sensing block for “when sprite clicked” because if I add a “touching mouse-pointer? and mouse down” block to an “if then” block inside a “forever” block to a sprite, the score variable will go up in the thousands instantly when I hold the mouse down on the sprite. This basically breaks the game I'm making and defeats the challenge.

You can do something like this:

forever
wait until <<mouse down?> and <touching [mouse-pointer v] ?>>
...
wait until <not <mouse down?>>
end