Pain and suffering are consequences of sin. Pain and suffering will end when Christ comes and establishes his earthly millennial kingdom, but even then with utopian life on this earth when Satan is released from the pit, he will lead nations into rebellion against Christ. This shows that fallen and unregenerate human heart is deceitful above all things and desperately wicked. After the last rebellion this present universe will be destroyed and in the Book of Revelation we see new heaven and new earth where righteousness will dwell. All unrepentant will be cast into the lake of fire along with Satan and his host, only then will there be eternal peace and rest without sufferings, pain, sin and death for ever and ever.
People blame God for pain, suffering and injustice, but if they would be honest they will see themselves as the ones causing all this. Generally speaking God simply allows us to do as we please to a point, as Sovereign He reserves the right to interfere in our affairs and often does in order to accomplish His will. Pain suffering and injustice is not caused by God but by fallen human heart influenced by father of lies Satan.
