Lips are burnt when I wake up

Once a week or so I wake up and my lips are burnt like a chemical burn. Its the same feeling as when I accidentally got tretinoin on my lips. But I've not been using tretinoin recently, nor anything exfoliating just my usual moisturiser. I can sleep walk so initially I thought I was sleep walking and outing tret on my lips, so I hid it and its not moved. I then thought it could be acid reflux as I can get that so I started doing prevention for silent reflux and I'm still waking up burnt. What could it be?