What did I do wrong with this GUI code?

This is just a LocalScript inside a ScreenGUI, its in StarterGui and everything. I get no errors in the output, and the GUI disappears the second I am in the game.

please help

local player = game.Players.LocalPlayer
local stats = player:FindFirstChild('leaderstats')
    if not stats then return end

local rep = stats:FindFirstChild('Reputation')
    if not rep then return end

local kills = stats:FindFirstChild('Kills')
if not kills then return end

while true do
    wait(1.5) 
    script.Parent.Hydration.Bar.Size = script.Parent.Hydration.Bar.Size - UDim2.new(0, 1, 0, 0)
    if script.Parent.Hydration.Bar.Size ~= UDim2.new(0, 0, 0, 15) then 
    end
    if script.Parent.Hydration.Bar.Size == UDim2.new(0, 0, 0, 15) then
        while true do
            wait(1.5)
            player.Character.Humanoid.Health = game.Players.LocalPlayer.Character.Humanoid.Health - 6
            if kills.Value == kills.Value + 1 then
            player.Character.Humanoid.Health = game.Players.LocalPlayer.Character.Humanoid.Health + 6
        end
        end
    else
    end
end