How do I fix jitter?

So I'm currently making a rigidbody fps controller and I'm getting t$$anonymous$$s jitter that comes in spurts. It's not horrible but becomes very bad when switc$$anonymous$$ng to slow motion. The jitter only happens when I'm walking around and looking at an object. The player is already interpolated as well.

Here's my player script:

 public class PlayerController : MonoBehaviour
 {
     //Components
     private Animator anim;
     private Rigidbody rb;
 
     //Movement
     Vector3 movement;
 
     //Speed and Sprinting
     private bool sprinting;
     private float speed;
     public float sprintSpeed = 750f;
     public float walkSpeed = 500f;
     public float stamina, maxStamina;
     public bool usingStamina;
 
     //Jump and Grouncheck
     public float jumpForce;
     public bool isGrounded;
     public Transform groundCheck;
     public float groundDistance = 0.4f;
     public LayerMask whatIsGround;
     
     public Vector3 airControl;
     public float airControlForce;
 
   
 
 
 
     // Start is called before the first frame update
     void Start()
     {
         rb = GetComponent<Rigidbody>();
         anim = GetComponent<Animator>();
        
     }
 
     // Update is called once per frame
     void Update()
     {
         movement.x = Input.GetAxisRaw("Horizontal") ;
         movement.z = Input.GetAxisRaw("Vertical");
 
         movement.Normalize();
 
         isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, whatIsGround);
            
         if (isGrounded)
         {
             Jump();
         }
 
         Sprint();
            
     }
 
     private void FixedUpdate()
     {
 
 
         if (isGrounded)
         {
 
             rb.velocity = rb.rotation * new Vector3(movement.x * speed * Time.deltaTime, rb.velocity.y, movement.z * speed * Time.deltaTime);
       
         }
                     
        if (!isGrounded)
         {
 
             rb.AddRelativeForce(movement.x * airControlForce, 0f, movement.z * airControlForce);
     
         }
   
     }
 
     private void Jump()
     {
 
         if (Input.GetKeyDown(KeyCode.Space))
         {
             rb.AddForce(jumpForce * transform.up);
         }
       
     }
 
     private void Sprint()
     {
         speed = walkSpeed;
 
         if (isGrounded)
         {
             if(Input.GetKeyDown(KeyCode.LeftS$$anonymous$$ft))
             {
 
                 sprinting = true;
 
             }
                         
         }
 
         if (Input.GetKeyUp(KeyCode.LeftS$$anonymous$$ft))
         {
 
             sprinting = false;
 
         }
 
        if(usingStamina)
         {
             if (sprinting && stamina >= 0f)
             {
                 speed = sprintSpeed;
                 stamina -= Time.deltaTime;
             }
             else if (!sprinting && stamina < maxStamina)
             {
                 stamina += Time.deltaTime;
             }
         }
        else if(sprinting)
         {
             speed = sprintSpeed;
         }
     
     }
    
     private void OnDrawGizmos()
     {
         Gizmos.DrawWireSphere(groundCheck.position, groundDistance);
     }
 
 }

And here's my camera script:

 public class CameraController : MonoBehaviour
 {
     public Vector2 mouseLook;
     [Range(0.0f, 100f)]
     public float sensitivity;
 
     private GameObject character;
     private Rigidbody rb;
     void Start()
     {
         Cursor.lockState = CursorLockMode.Locked;
         Cursor.visible = false;
         character = transform.parent.gameObject;
         rb = character.GetComponent<Rigidbody>();
     }
 
     private void LateUpdate()
     {
         mouseLook.x += Input.GetAxis("Mouse X") * sensitivity;
         mouseLook.y += Input.GetAxis("Mouse Y") * sensitivity;
         mouseLook.y = Mathf.Clamp(mouseLook.y, -90f, 90f);
 
 
         transform.localRotation = Quaternion.AngleAxis(-mouseLook.y, Vector3.right);
         rb.MoveRotation(Quaternion.AngleAxis(mouseLook.x, rb.transform.up));
     }
 
 
 }

I'm going to assume it has somet$$anonymous$$ng to do with updates vs fixed updates but I can't figure out what I did wrong.