Strange vibrating when moving camera view

I want this to move above the player in a circular movement and always face the player, and have it clamped between behind the player and above him.

 using UnityEngine;
 using System.Collections;
 
 public class CameraController : MonoBehaviour {
     
     public int Sensitivity;
     
     private float MouseY;
     private float MouseYSet;
     private float XRot;
     private float YPos;
     private float ZPos;
     
     public GameObject CameraTarget;
     
     void Start () {
         
     }
     
     void Update () {
         // Rotation controls
         MouseY += Input.GetAxisRaw ("Mouse Y");
         transform.localRotation = Quaternion.Euler (Mathf.Clamp (transform.localRotation.x, 0, 90), transform.localRotation.y, transform.localRotation.z);
         transform.localPosition = new Vector3 (transform.localPosition.x, Mathf.Clamp (transform.localPosition.y, CameraTarget.transform.localPosition.y + CameraTarget.transform.lossyScale.y / 2, CameraTarget.transform.localPosition.y + 50), Mathf.Clamp (transform.localPosition.z, CameraTarget.transform.localPosition.z, CameraTarget.transform.localPosition.z + 50));
         if (MouseYSet != MouseY)
         {
             transform.Rotate (new Vector3 (-(MouseY - MouseYSet) * Sensitivity * 10, 0, 0));
             transform.Translate (new Vector3 (0, -(MouseY - MouseYSet) * Sensitivity * 10, -(MouseY- MouseYSet) * Sensitivity * 10));
             MouseYSet = MouseY;
         }
     }
 }