Q: May I ask, when it comes to suffering, particularly of the chronic physical type, is this all a result of inflicting such pain on others in a past life?
Karma works very exactly. Karma is extremely complex because exactly what we did must come back to us. It does not get bundled up with various types of causes and result in an unspecific form.
For example, if you inflict pain on someone, then someone will inflict pain on you. Physical illness or suffering can be caused by having neglected or or even done deliberate harm to our body in anger or some other negative emotion, including self-loathing. Unsuccessful attempts at suicide can be a cause of present pain.
Or is it a combination of that and obstacles set in place (by a higher self) to help us grow and develop?
No. Neither our higher self or God ever decide that we need “a good kicking around” for our own “good.” We do not get karmically spanked for “being bad.” The reaping of negative karma is not retribution.