So I'm trying to make a combo with multiple attacks per layer, and not sure how.

I'll post the script here, and a bit about where the issue is.

public class ComboCoro : MonoBehaviour { public GameObject target;

 public string ComboLast;
 public int MBCurrent;
   
 // Use this for initialization
 void Start() {
     ComboLast = "0N";
 }


 void FixedUpdate() {
     if (Input.GetMouseButtonUp(0) && ComboLast == "0N")
     {

         StartCoroutine("ComWin");
         
      
     }
 }
 //combo attacks
 void A1Ice()
 {
     EnemyHealth eh = (EnemyHealth)target.GetComponent("EnemyHealth");
     eh.AdjustCurrentHealth(-10);
     ComboLast = "A1Ice";
 }
 void A2Ice()
 {
     EnemyHealth eh = (EnemyHealth)target.GetComponent("EnemyHealth");
     eh.AdjustCurrentHealth(-10);
     ComboLast = "A2Ice";
 }
 void A2Fire()
 {
     EnemyHealth eh = (EnemyHealth)target.GetComponent("EnemyHealth");
     eh.AdjustCurrentHealth(-5);
     ComboLast = "A2Fire";
 }
 IEnumerator ComWin()
 {
     if (Input.GetMouseButtonUp(0) && ComboLast == "0N")
     {
         A1Ice();
         yield return new WaitForSecondsRealtime(1.0f);
      
         yield return StartCoroutine(ComWin2());

         
     }
    
     {
         A2Ice();
         yield return new WaitForSecondsRealtime(1.0f);
         ComboLast = "A2Ice";
         Debug.Log(ComboLast);
     }
     {
         A2Fire();
         yield return new WaitForSecondsRealtime(1.0f);
         ComboLast = "A2Fire";
         Debug.Log(ComboLast);
     }
 }
 IEnumerator ComWin2()
 {
     while (!Input.GetMouseButton(0) && ComboLast == "A1Ice")
         yield return null;
 }

}

I'm basically trying to create a system where based on the mouse button pressed, it performs a different attack. The only thing I can think of that would even begin to work is stack based FSM, but i don't understand them at all ): , any suggestions would be greatly appreciated <3