First of all, it’s important to note that such physical ailments are merely the result of natural causes. It is part and parcel of the material world that God decided to make—that is a world void of a perpetual miracle.
Secondly, God’s allowance of suffering is a mystery. The Catechism of the Catholic Church acknowledges this in paragraph 309.
Now, by acknowledging it as a mystery does not mean it is unreasonable.
For example, we know by faith that all human suffering is a result of the fall. If Adam and Eve had remained in Divine intimacy with God, then all humans would have been free from suffering (see Catechism of the Catholic Church 376).
Furthermore, it is perfectly in accord with God’s goodness to permit suffering if there is a greater good that He knows and wills to bring about. For example, I allow my wife to cause suffering to the children when she pours peroxide on their cuts even when I have the power to stop her. But this doesn’t account against my goodness because I know of the greater good that will come from the permitting this form of suffering. Similarly, because there is no good that God cannot bring about due to His omnipotence, His permission of suffering does not count against His goodness.
For a further explanation of the problem evil, you might want to purchase Trent Horn’s book
Answering Atheism.
Here are some articles that serve as snippets of what Trent covers in the book:
catholic.com/blog/matt-fradd/the-problem-of-evil
catholic.com/blog/trent-horn/why-horrible-suffering-does-not-disprove-gods-existence