I never seem to be terribly helpful to you, but here goes...
First, have you tried switching the order of the last two events, so you'd be creating an instance of the counter AFTER you've subtracted the enemy's hit points from it?
Secondly, how are you limiting the value setting and creation of the counters? I assume all these events occur when Zero collides with the enemy. Have you tried only allowing the counter to be set to a random variable when a flag is off? Then, when the counter is created, set that flag on (this should prevent the multiple pop-ups).
Is that any help?