Help with my camera script that's not working correctly?

I'm creating a first person game where it is crucial to be able to look straight up and straight down, but the maximum is 80 degrees. So, I looked inside the root camera script, found the numbers, but it seems that the way Roblox's camera works is hard coded to be max 80 degrees without breaking down. So I'm making a new camera script and have been working off of this for about a day now, with no luck.

local camera = workspace.CurrentCamera
camera.CameraType = Enum.CameraType.Scriptable
camera.CameraSubject = workspace.blockHold.PreCreated.Part
camYaw = 90
camYZ = 0
_G.XMouse = 0
_G.YMouse = 0

local UserInputService = game:GetService("UserInputService")

UserInputService.MouseBehavior = Enum.MouseBehavior.LockCenter

UserInputService.InputChanged:connect(function(inputObject)
    if inputObject.UserInputType == Enum.UserInputType.MouseMovement then
        _G.XMouse = inputObject.Delta.x
        _G.YMouse = inputObject.Delta.y
        camYaw = camYaw + _G.XMouse
        camYZ = camYZ + _G.YMouse
        if camYZ >90 then camYZ=90 end
        if camYZ <-90 then camYZ=-90 end
        camera.CoordinateFrame = CFrame.new(0,0.1,0)
                             *CFrame.Angles(math.rad(math.cos(math.rad(camYaw))*-camYZ),math.rad(-camYaw),math.rad(math.sin(math.rad(camYaw))*-camYZ))
        end
end)

The script almost works, but looking in certain directions rotates the camera oddly.

Any ideas of what I'm doing wrong? I've been slightly tweaking this code for a while but I'm now just completely stuck. The local script is named CameraScript and is in StarterPlayer>StarterPlayerScripts. I also don't really know trig if that clears anything up. Thanks in advance for any changes you might have.