Simple Flying script (JS possibly)

Hi guys, i've a problem I've tried to create a script that allows flying for my character, it's pretty simple: press A or D: rotate around the Y axis press W: rotate around the X axis so that my character looks up (45° max) press S: rotate around the X axis so that my character looks down (-45° max) all this while my character goes straight forward in the direction of transform.forward

This is the script i've written right now:

 var speed : float = 20;
 
 var rotX : float;
     
     function Update () {
     
     CC.Move(transform.forward * Time.deltaTime * speed);
     
     rotX=transform.rotation.x;
     
     if(Input.GetKey(KeyCode.A)) {
     transform.rotation.y=transform.rotation.y - (1 * Time.deltaTime);
     }
     
     if(Input.GetKey(KeyCode.D)) {
     transform.rotation.y=transform.rotation.y + (1 * Time.deltaTime);
     }
     
     if(Input.GetKey(KeyCode.W) && rotX>-0.25) {
     transform.rotation.x=transform.rotation.x - (1 * Time.deltaTime);
     }
     
     if(Input.GetKey(KeyCode.S) && rotX<0.25) {
     transform.rotation.x=transform.rotation.x + (1 * Time.deltaTime);
     }
     
     }

But here i got a problem: the rotations after a while mess a little, also the Z axis rotation changes and that creates a lot of problems. Also, i need that my charater can rotate more than 1 time around his Y axis, but with this code it can't.

I hope someone of you can give me some adviices, and sorry if i've done some grammar errors. Thank you