How does the 2nd Noble truth explain the cause of suffering-as-suffering (e.g. resulting from a severe burn)?
Dukkha-dukkha is just painful feelings accompanied by craving. Painful feelings are simply feelings. In the case of severe burns, one would experience a lot of painful feelings. But it is still just a physical feeling like any other physical feeling. It becomes suffering only when you wish it to go away. That is called Vibhava-tanha. In other words, the craving for a certain experience to go away causes you suffering.