God did not create pain and sorrow. We did.
God loves us perfectly and unconditionally, but he set parameters. Through sin, which is a rejection of God’s love, sin and death were brought into the world. We are fallen creatures, and we have damaged our dignity. Unfortunately, the repurcussions from sin do not remain with the individual but affect us all.
But God in his abundant love, sent his only Son, Jesus, to overturn the sin of Adam, and in the Paschal mystery we find the answers.
I would actually encourage you to pick up JPII’s Apostolic Letter, Salvifici Doloros, for he answers your questions. Rather, he helps you to see how GOD answers those quesitons. In the Letter, he explaines how in the depths of our suffering, it is human nature to question it, and He expects us to answer those questions. But they cannot be answered apart from the cross.
In Jesus’ very life and death, he restored the dignity of the human person fully, and he actually elevated suffering and invited us to partake in it. In the Letter, the scriptural references are there and I even encourage you to follow the footnotes.
I actually had to write a paper on this topic (similar) this last semester, and by following the footnotes wth the scriptural references, my eyes were opened even wider.
So ask your questions, but go to the experts for the answers, go to prayer, and in silence, allow the Lord to answer you and show you suffering in the shadow and the glory of the Cross of Christ.