John 9:2-3 His disciples asked him, “Rabbi, who sinned, this man or his parents, that he was born blind?” “Neither this man nor his parents sinned,” said Jesus, “but this happened so that the works of God might be displayed in him.
Sometimes God allows it to show his glory in such situations. So I agree, biblically speaking not all suffering is the result of discipline or God’s punishment. However, we cannot box God in and say, “He never sends suffering” in some cases he does, so people will repent of willful disobedience to get our attention. And ultimately get us to correct our ways! Even when he directly sends it he does so with hopes of good results.
1 Corinthians 11:32 Nevertheless, when we are judged in this way by the Lord, we are being disciplined so that we will not be finally condemned with the world.
Jesus also said to one of the churches in Rev
Revelation 2:22 So I will cast her on a bed of suffering, and I will make those who commit adultery with her suffer intensely, unless they repent of her ways.
God would rather in some cases cause a person temporal grief in this life than totally abandon them in the next.
So whether God sends suffering or allows it is not as important as who we know God to be, loving and good. He uses pain ultimately for our good. We must respond to it rightly either way.