Why my Player GameObject keeps on mooving anyway on its own without my input?

Hi All,

Sorry for my bad english!

I'm very beginner in unity I have a minigame 2D made of just 3 Levels, in which i have My Player, that is a simple Game Object with a animated sprite, and at some moments of the game, i istantiate some animated prefabs that i connect to the Player, making the prefabs children of the player. Then, i can drag the Player it by mouse(PC) or by touch(Android/Iphone) insiede a very simple Maze o few streets. I use the rigid body connected to the player. I program everything by C#. My problem is this: At the Level 1 everything works good, it means that my player mooves when i put a dragging input by mouse or touch and stop to mooves when i stop to drag or touch. At the level 2 and 3, instead, when i stop draging or touching the player, the players keeps on mooving on it's own as if someone else was touching it. How is my player able to moove its own without my input? I don't know how to fix this bug. Please help me. Thank you very much for all the future help

The next is a part of the script attached to my Player. It's in C#

 void Update()
          {
             if (Input.touchCount > 0) 
     {
         TouchPhase touchphase= Input.GetTouch(0).phase;

         switch (touchphase)
         {
         case TouchPhase.Began:
                    animator.SetInteger("a", 1); //mooving
             break;
     
         case TouchPhase.Stationary:
             animator.SetInteger("a", 0); //idle
             break;
         case TouchPhase.Moved:    
                     animator.SetInteger("a", 1); //mooving
                      float x = Input.GetAxisRaw("Mouse X");
             float y = Input.GetAxisRaw("Mouse Y");
         Vector2 pos = new Vector2 (Input.GetTouch (0).position.x, Input.GetTouch (0).position.y);
             pos = Camera.main.ScreenToWorldPoint (pos);    
                //in the Start() function, rb2d = this.gameObject.GetComponent<Rigidbody2D> ();
             rb2d.MovePosition (pos); 
                 break;

         case TouchPhase.Ended:
             animator.SetInteger ("a", 0); //idle
                 break;
         }

}

//-------------------------------------------------------------------------------------------

 void OnMouseDrag()
     {
 
         float x = Input.GetAxisRaw ("Mouse X");
         float y = Input.GetAxisRaw ("Mouse Y");
         
         Vector2 pos = new Vector2 (Input.mousePosition.x, Input.mousePosition.y);
         
         pos = Camera.main.ScreenToWorldPoint (pos);    
 
         rb2d.MovePosition (pos);
         
     }