Multiplying a feed after kill

I have a score feed, which displays a text that says "15+" when ever i kill an enemy, but the problem is, if i shoot multiple enemies in a small time range it will just show "15+" throughout it, so it would be hard to distinguish between each kill. I want it to double whenever i get multiple kills within a certain time range (i know it says multiply in the title, but it looks better.). Here is an example from CoD: https://www.youtube.com/watch?v=aU8OKGlYpfk

I've searched it up, but i still can't find a good solution, i've been pondering for a while now.

XP feed code, that pops up a text (saying 15+) whenever i kill someone:

  public class XpFeed : MonoBehaviour {
 
     public float showtime;
     Text text;
     public int xpFeed;
 
     void Awake()
     {
         // Set up the reference.
         text = GetComponent<Text>();
 
         // Reset the score.
     }
 
     void Update()
     {
         // Set the displayed text to be the word "Score" followed by the score value.
         text.text = "+" + xpFeed + "xp";
     }
 
     public void getFeed()
     {
         StopCoroutine("showfeed");
         text.enabled = true;
         StartCoroutine("showfeed");
     }
 
     public IEnumerator showfeed()
     {
         yield return new WaitForSeconds(showtime);
         text.enabled = false;
     }
 }

And enemy AI code:

 public class AIHealth : MonoBehaviour
 {
 
     public int xpValue = 15;
     public GameObject xpfeed;
     
     void Awake()
     {        
         xpfeed = GameObject.Find("XPFeed");
     }
 
     void Death()
     {
         XPManager.curXp += xpValue;
         xpfeed.GetComponent<XpFeed>().getFeed();
     }
 }