damaging block hurt player

Hi there !

I made a simple mod element to hurt player if he try to break a block without tool, yet it only detect the FIRST blow. If the player maintain the left click button, the procedure is not working...

So I try this one. It compile and I can run minecraft but as soon as I click a block, My CPU overreact, goes full 100% on all cores and the game freeze...

How can I fix my procedure so that it keep looping as long as the player maintain left click ?

Thanks in advance for the help !