How can I spawn different GameObjects using IEnumerator?

Hi!

I've been searching all day and I still can't find an answer, so let's get straight to the point. My game has two principal scripts that control everything, the first, named "Game_Controller" has access to score, and the second named "Object_Spawner", is responsible for spawning GameObjects according to the score in Game_Controller.

If score > 5, Object_Spawner will spawn a different GameObject, it's like creating a new wave of enemies.

For that, I'm using IEnumerator and coroutines to start and stop a wave, the first wave spawn seems to work fine, but the problem is when I start the second wave it will just spawn hundreds of objects at high speed. Please note that I'm using a random timer in order to spawn objects at random time. I think the issue with the second wave has something to do with the timer.

The problem is when I start coroutine diamond. Please if there's something bad in my code please notify me, Im just 17.

Thaanks!

CODE (Object_Spawner):

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class Object_Spawner : MonoBehaviour {
 
     private float Timer;
     public GameObject wave_Cam;
     public Text wave_Text;
 
     public Transform spawner;
     public GameObject victim;
     public GameObject Clone;
 
     public Transform diamond_Spawner;
     public GameObject diamond_Obstacle;
     public GameObject diamond_Clone;
 
     public IEnumerator coroutine_Triangle;
     public IEnumerator coroutine_Diamond;
 
     // Use this for initialization
     void Start () {
         
         RandomTimer();
 
         coroutine_Triangle = Callvictim (); // Assign function to variable coroutine_Triangle
         StartCoroutine(coroutine_Triangle); // On start run Triangle coroutine
 
         coroutine_Diamond = callDiamond (); // Assign function to variable coroutine_Diamond
         StopCoroutine (coroutine_Diamond); // On start don't run Diamond coroutine
 
         // coroutine_Gear = callGear(); // Assign function to variable coroutine_Diamond
         // StopCoroutine (coroutine_Gear); // On start don't run Gear coroutine
     }
 
     void RandomTimer()
     {
         Timer = Random.Range(0.9f , 1.8f);
     }
 
 
     void spawnVictim(){ // Spawn Triangle function
             Clone = Instantiate (victim, spawner.transform.position, spawner.rotation) as GameObject;
             Clone.GetComponent<Rigidbody2D> ().AddForce (Vector2.left * 300);
     }
 
     void spawnDiamond(){ // Spawn Diamond function
         diamond_Clone = Instantiate (diamond_Obstacle, diamond_Spawner.transform.position, diamond_Spawner.rotation) as GameObject;
         diamond_Clone.GetComponent<Rigidbody2D> ().AddForce (Vector2.left * 380);
     }
 
     IEnumerator Callvictim() // Start Callvictim to spawn triangles by random time
     {
         //---------------------------------------------------------// WAVE ACTIVATOR
         wave_Text.text = "WAVE 1";
         yield return new WaitForSeconds (1);
         wave_Cam.SetActive (true);
         yield return new WaitForSeconds (2);
         wave_Cam.SetActive (false);
         //---------------------------------------------------------//
 
         while (true) {
             spawnVictim ();
             yield return new WaitForSeconds (Timer);
             RandomTimer ();
         }
             
     }
 
     IEnumerator callDiamond() // Start callDiamond to spwan Diamonds by random time **--PROBLEM--**
     {
         while (true) {
             spawnDiamond ();
             yield return new WaitForSeconds (Timer);
             RandomTimer ();
         }
     }
         
         
 
     public void stop_Coroutine_Triangle(){ // Stop top Triangle coroutine
         StopCoroutine (coroutine_Triangle);
     }
 
     public void start_Coroutine_Diamond(){ // Start top Diamond coroutine
         StartCoroutine (coroutine_Diamond);
     }
 
     public void stop_Coroutine_Diamond(){ // Stop top Diamond coroutine
         StopCoroutine (coroutine_Diamond);
     }
 
 
 
     void Update(){
     }
 }

CODE (Game_Controller):

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Game_Controller : MonoBehaviour {
 
     public GameObject up_Plane;
     public int accessedCount;
 
     // Use this for initialization
     void Start () {
         access_Count (); // Execute function on start
     }
 
     void access_Count(){ // Get access to count int located in a different script
         accessedCount = up_Plane.GetComponent<GO_UP> ().count;
     }
 
     void check_points(){
         
         if (accessedCount > 2) { // Triangle wave
             Camera.main.GetComponent<Spawner_Up> ().stop_Coroutine_Triangle();
             Camera.main.GetComponent<Spawner_Down> ().stop_Coroutine_Triangle_2();
         }
 
         if (accessedCount > 4) {
             Camera.main.GetComponent<Spawner_Up> ().start_Coroutine_Diamond();
         }
 
         if (accessedCount > 5) {
             Camera.main.GetComponent<Hex_Spawn> ().enabled = true;
         }
     }
     
     // Update is called once per frame
     void Update () {
         check_points (); // Execute function to check points
         access_Count (); // Execute function to update points
     }
 
 }

I think the problem is at IEnumerator callDiamond();