Unity camera spinning around uncontrollably

I’m trying to clamp the camera rotation but when doing so the camera spins out uncontrollably. I tried it with Math.fClamp and another way and both seem to do the exact same thing.

Here is the code that I use:
using UnityEngine;
using System.Collections;

public class CameraController : MonoBehaviour {

	
	float mRotY;
	
	void Start () {
		if(rigidbody)
			rigidbody.freezeRotation = true;
			
		if(!Debug.isDebugBuild)
			Screen.lockCursor = true;
		else
			Screen.lockCursor = false;
		
	}
	
	
	void FixedUpdate () {
		
		mRotY = Input.GetAxis ("Mouse Y") * GameManager.sensitivity * Time.deltaTime;
		if(mRotY>270.0f)
			mRotY = 270.0f;
		if(mRotY<90.0f)
			mRotY = 90.0f;
//		
		transform.Rotate(mRotY, 0.0f,0.0f);
		
	}
}

The problem is you aren’t clamping the rotation, you are clamping the speed that the rotation changes.

Also you are setting any rotation speed less than 90 to be equal to 90, hence why the camera spins out.