Instantiate a COMPLETELY Unique Instance of an Object

Hey, right now I'm instantiating a number of various types of a GameObject. There are a number of different prefabs and the scripts tells the game which prefab to instantiate based on a button press. I'm instantiating them by setting them equal to a temporary value, which I thought made them unique of each other, but when a static variable changes in one instance, it changes in all of them, which I don't want to happen. I tried to Instantiate into an array of GameObjects and increase the element that the game is going to create the next GameObject in, however when I did that, all of the code beneath it seemed to be ignored (allowing the player to spawn hundreds of these prefabs at a time).

So my question is, is there a better way to Instantiate a Prefab of a GameObject into the scene and make it completely unique from all other similar instances of that GameObject? Thanks ahead of time :)

Since everyone wants to see my code, I'll post some of it. The whole script is a good 800 lines, so this is just the snippet I'm directly referring to for the sake of Instantiating:

 if (placeAnimal == true && notSpawn == true)
         {
             notSpawn = false;
         }
         else if (placeAnimal == true && notSpawn == false)
         {
             if (Input.GetKeyDown(KeyCode.Mouse0) && placeAnimal == true)
             {    
                    Debug.DrawRay (placeRay.origin, placeRay.direction * rayLength, Color.green);
                 print("Ray Drawn");
             
                 placeRay = Camera.main.ScreenPointToRay (Input.mousePosition);
             
                 if (Physics.Raycast (placeRay, placeHit, rayLength))
                   {
                     placeHitVector = placeHit.point;
                    }  
     
                 
                 if (placeHit.collider.gameObject.tag == cageToCheck)
                 {
                     UpdateNewsFeed();
                     script_ParkManager.newsFeed[0] = "You purchased a " + animalToPlace.gameObject.tag + ".";    
                 
                     animalToPlace.transform.position = script_DetermineClickedObjects.currentHitSpot;
                     spawnedAnimalInstance = Instantiate(animalToPlace, testHit, Quaternion.identity);                
                     placeAnimal = false;
                     script_ParkManager.currentMoney -= moneyToRemove;
                     animalToPlace = null;
                     targetToggle = false;
                 }
                 else
                 {
                     UpdateNewsFeed();
                     script_ParkManager.newsFeed[0] = "Failed to place " + animalToPlace.gameObject.tag + ".";    
                     
                     placeAnimal = false;
                     animalToPlace = null;
                     targetToggle = false;
                 }
             }
         }

Now as for the GetComponent part of the script, in this instance I have an animal who can get sick over time based on a couple variables. isSick is a static var so that a Veterinarian can see the sick animal and heal it.

 function UpdateHealth () {
 
     sickRandom = Random.Range(0,101);
     
     if (sickRandom <= sickMinRange && isSick == false)
     {
         GameObject.FindGameObjectWithTag("MainObject").GetComponent(script_HUDBuild).UpdateNewsFeed();        
         if (!(animalName == ""))
         {
             script_ParkManager.newsFeed[0] = "" + animalName + " the " + this.gameObject.tag + " is sick! Make sure you have a Medical Aid to cure them.";
         }
         else
         {
             script_ParkManager.newsFeed[0] = "A " + this.gameObject.tag + " is sick! Make sure you have a Medical Aid to cure them.";
         }
                 
         sickObject = Instantiate(sickAnimation, transform.position, transform.rotation);        
         isSick = true;
         InvokeRepeating("Sick", 1.0, 2.0);
     }
 
 }

Now here is the script for the Veterinarian. He collides with the animal in order to heal him.

 #pragma strict
 
 var medicalSkill        : int;
 
 function Start () {
 
 }
 
 function Update () {
 
 }
 
 function OnTriggerEnter ( other : Collider) {
 
     if (other.gameObject.tag == "Zebra" || other.gameObject.tag == "Elephant" || other.gameObject.tag == "Tiger" || other.gameObject.tag == "Bear" || other.gameObject.tag == "Giraffe" || other.gameObject.tag == "Monkey")
     {
         if (other.gameObject.GetComponent(script_Animal).isSick == false)
         {
             GameObject.FindGameObjectWithTag("MainObject").GetComponent(script_HUDBuild).UpdateNewsFeed();
             script_ParkManager.newsFeed[0] = "A Medical Aid has cured a " + other.gameObject.tag + ". Congratulations!";
         }
             
         other.gameObject.GetComponent(script_Animal).animalHealth += Random.Range(10,51);    
         other.gameObject.GetComponent(script_Animal).isSick = false;
         other.gameObject.GetComponent(script_Animal).sickMinRange -= Random.Range(20, 51);
     }
 
 
 }

Am I wrong to use a static var here then? Should I be setting the GetComponent(script_Animal) equal to a

 var scriptInstance : script_Animal; 

or something along those lines?