Maybe we didn’t eat as nutritionally as we could. Maybe we are careless or overindulge. We don’t want to blame all this on Karma. Karma isn’t like that anyway, giving out pain as punishment. It is more about how you face your life when you are ready to cross over. How much love did you show?
Humans often want all the pleasure of the body but we often don’t understand the yin/yang of pleasure and pain. Are we going to have all the pleasure and fun and none of the pain? That is not how the Universe manifests itself. Actually, people who cannot feel pain at all, die at an early age because they can bite their tongues or seriously injure themselves and just bleed to death because they have not sought help.
Don’t blame yourself for your pain. You don’t need that added psychlogical burden to your discomfort. Separate the pain from the suffering and see the difference. You can’t choose the pain, but you can choose the suffering (or not to suffer).
Yet pain has nothing to do with who you really are, as a Soul. The Soul feels nothing of pain or distress. It is not physical.