I can't see the bottom - free camera script

-- 3/1/2019 free camera script by Valualty --
-- twitter: @Valualty --
SPEEDY_DRIFTY = 0.7 -- studs every 1/60 seconds
x_degree = 2.5 -- degrees every 1/60 seconds
y_degree = 1.4 -- degrees every 1/60 seconds
plr = game.Players.LocalPlayer
repeat
    wait()
until plr.Character
mouse = plr:GetMouse()
cam = workspace.CurrentCamera
hum = plr.Character.Humanoid
oldspeed = hum.WalkSpeed
run = game:GetService('RunService')



-----------------------------------------------------------------------
plr.PlayerScripts.CameraScript:Destroy()
game:GetService('UserInputService').MouseBehavior = 'Default'
game:GetService('UserInputService').MouseIconEnabled = true
-----------------------------------------------------------------------



screensize = cam.ViewportSize

w,s,a,d,q,e = false,false,false,false,false,false -- position
rr,rl,ru,rd = false,false,false,false -- rotation
ded = false
tog = true

pp = Instance.new('Part')
pp.Transparency = 1
pp.TopSurface = 0
pp.BottomSurface = 0
pp.Anchored = true
pp.CanCollide = false
pp.Parent = cam
ll = Instance.new('PointLight')
ll.Range = 60
ll.Brightness = 1
ll.Parent = pp

keydown = mouse.KeyDown:Connect(function(key)
    if key == 'w' then w = true end
    if key == 's' then s = true end
    if key == 'a' then a = true end
    if key == 'd' then d = true end
    if key == 'q' then q = true end
    if key == 'e' then e = true end

    if hum.Health > 0 then
        if key == string.lower('f') then
            if tog then
                tog = false
            else
                tog = true
            end
        end
    end
end)
keyup = mouse.KeyUp:Connect(function(key)
    if key == 'w' then w = false end
    if key == 's' then s = false end
    if key == 'a' then a = false end
    if key == 'd' then d = false end
    if key == 'q' then q = false end
    if key == 'e' then e = false end
end)

died = hum.Died:Connect(function()
    ded = true
end)

mousemove = mouse.Move:Connect(function()
    x = mouse.X
    y = mouse.Y
    if x / screensize.X <= 0.1 then
        rl = true
    else
        rl = false
    end
    if x / screensize.X >= 0.8 then
        rr = true
    else
        rr = false
    end
    if y / screensize.Y <= 0.15 then
        ru = true
    else
        ru = false
    end
    if y / screensize.Y >= 0.8 then
        rd = true
    else
        rd = false
    end
end)

while ded == false do
    if tog == true then
        cam.CameraType = 'Scriptable'
        cam.CameraSubject = pp
        pp.CFrame = cam.CFrame
        hum.WalkSpeed = 0
        if w then
            cam.CFrame = cam.CFrame * CFrame.new(0,0,-SPEEDY_DRIFTY)
        end
        if s then
            cam.CFrame = cam.CFrame * CFrame.new(0,0,SPEEDY_DRIFTY)
        end
        if a then
            cam.CFrame = cam.CFrame * CFrame.new(-SPEEDY_DRIFTY,0,0)
        end
        if d then
            cam.CFrame = cam.CFrame * CFrame.new(SPEEDY_DRIFTY,0,0)
        end
        if q then
            cam.CFrame = cam.CFrame * CFrame.new(0,-SPEEDY_DRIFTY,0)
        end
        if e then
            cam.CFrame = cam.CFrame * CFrame.new(0,SPEEDY_DRIFTY,0)
        end

        -- WORKS IN FIRST TRY --
        -- rotating is in global --
        if rl then
            camrot = cam.CFrame - cam.CFrame.p
            cam.CFrame = CFrame.new(cam.CFrame.p) * CFrame.Angles(0, math.rad(x_degree), 0) * camrot
        end
        if rr then
            camrot = cam.CFrame - cam.CFrame.p
            cam.CFrame = CFrame.new(cam.CFrame.p) * CFrame.Angles(0, math.rad(-x_degree), 0) * camrot
        end
        -- rotating x can't be in global --
        if ru then
            cam.CFrame = cam.CFrame * CFrame.Angles(math.rad(y_degree), 0, 0)
        end
        if rd then
            cam.CFrame = cam.CFrame * CFrame.Angles(math.rad(-y_degree), 0, 0)
        end
    else
        hum.WalkSpeed = oldspeed
        cam.CameraType = 'Custom'
        cam.CameraSubject = hum
    end
    run.RenderStepped:Wait()
end
keydown:Disconnect()
keyup:Disconnect()
died:Disconnect()
mousemove:Disconnect()
pp:Destroy()
cam.CameraType = 'Custom'
cam.CameraSubject = hum