Managing multiple images fillamount by one function?

I want to fill the button that I clicked but when I click multiple buttons the button that I clicked before stops and the other button starts.

That's the script :

 public function ActionTime (actionSeconds : float) 
 {
 actionTime = actionSeconds;
 actionTimeComplete = actionSeconds;
 
 }
 
 //COOLDOWN IMAGES
 public function CooldownImage (imageForCooldown : Image)
 {
 imageCooldown = imageForCooldown;
 CooldownFunction();
 }
 
 public function CooldownFunction ()
 {
 var actionTime = 0f;
 imageCooldown.fillAmount=actionTime;
 imageCooldown.GetComponent(Button).interactable = false;
 
 while(actionTime < actionTimeComplete )
 {
 actionTime += Time.deltaTime;
 imageCooldown.fillAmount=actionTime/actionTimeComplete;
 yield;
 }
 moneyGlobal+=moneyToGive;
 XPGlobal+=xpToGive;
 imageCooldown.GetComponent(Button).interactable = true;
 }
 

Everything works fine until I click another button. Basically that script can complete one image fillamount at once , how can I manage to complete multiple images without creating a bunch of functions?