Collision based on array of enemies

Hello all,

New to C# here, any programming language on that note. I am teaching myself C# by making a little game and found myself running into an issue. I have created an array of enemies at the beginning of my code, when a play collides with an enemy, the play is knocked back a short distance (Currently using around 8 force). This is working great when there is only a single enemy, however if add more the one enemy, it will base the collision script on what ever the highest enemy is within the array.

I am using loop that will looking for enemies in the array but can't seem to get this fixed. Any help would be most appreciated. Here is my script below;

 using UnityEngine;
 using System.Collections;
 
 public class Movement : MonoBehaviour 
 { 
     public float maxSpeed = 10f;    // Character movement speed.
     public bool grounded = false;     //is the Character grounded?
     public Transform groundCheck;     // Used for creating grounded 
     float groundRadius = 0.2f;        //
     public LayerMask whatIsGround;    // Marker to show where the ground is
     float jumpForce = 15f;            // Force for vertical velocity (jumping)
     float knockForce = 8f;            // Force which the character will be knocked on both axis        
     float travelTime = 0.1f;        // Timer to set how often the timer will check for grounded to reset velocity
     public float doubleJump = 1;    // Double jump limit
     bool movement = true;            // Disables movement during knockbacks
     public int enemyIndex = 0;             // Used to check array each from in a enemyIndex++
     Vector3 enemy_pos;
 
     private GameObject[] Enemy;
 
     void Start(){
         Enemy = GameObject.FindGameObjectsWithTag ("Enemy");    // Define what is Enemy using tag Enemy 
         enemy_pos = Enemy[enemyIndex].transform.position; // Define the position of the Enemy array
 
     }
 
 
     void Update(){
         enemyPosition ();
 
 
         grounded = Physics2D.OverlapCircle (groundCheck.position, groundRadius, whatIsGround);    // Checks for grounded        
 
         if (movement) {
 
         // Character Movement
         if (Input.GetKey (KeyCode.A)) {
             transform.position += Vector3.left * maxSpeed * Time.deltaTime;
         }
         if (Input.GetKey (KeyCode.D)) {
             transform.position += Vector3.right * maxSpeed * Time.deltaTime;
         }
         if (Input.GetKey (KeyCode.W)) {                
             transform.position += Vector3.up * maxSpeed * Time.deltaTime;
         }
         if (Input.GetKey (KeyCode.S)) {
             transform.position += Vector3.down * maxSpeed * Time.deltaTime;
         }
         }
 
         // Jumping 
         if (grounded && Input.GetButtonDown ("Jump")) {
             rigidbody2D.velocity = new Vector2 (0, jumpForce);
         }
 
         // Double jump
         if (!grounded && Input.GetButtonDown ("Jump") && doubleJump > 0) {
             rigidbody2D.velocity = Vector2.zero;
             rigidbody2D.velocity = new Vector2 (0, jumpForce);
             doubleJump = 0;
                 } else if (grounded == true) {        
                     doubleJump = 1;
                 }
     }
 
     void OnCollisionStay2D(Collision2D coll) {
         if (coll.gameObject.tag == "Enemy") {
         //    rigidbody2D.velocity = new Vector2 (-8, 8); -- Old Code
             rigidbody2D.velocity = (knockForce * (transform.position - enemy_pos));
             Debug.Log (knockForce * (transform.position - enemy_pos));
             StartCoroutine (knockBack (travelTime));
             movement = false;
 
         }
     
     }
 
     IEnumerator knockBack(float travelTime) {
         yield return new WaitForSeconds (travelTime);
         movement = true;
         if (!grounded) {
             StartCoroutine (knockBack (travelTime));
             movement = false;
         }
         if (grounded){
             rigidbody2D.velocity = Vector3.zero;
         }
     }
 
     void enemyPosition(){
         enemyIndex++;
         if (enemyIndex >= Enemy.Length);
         Debug.Log (Enemy.Length);
             enemyIndex = 0;
         }
 
 }
 

Please don't mind the pretty messy code. Will clean that up as I near the end of this particular script!