| Quote #4
With this consciousness, and with physical pain besides the terror, he must go to bed, often to lie awake the greater part of the night. Next morning he had to get up again, dress, go to the law courts, speak, and write; or if he did not go out, spend at home those twenty-four hours a day each of which was a torture. And he had to live thus all alone on the brink of an abyss, with no one who understood or pitied him. (4.27)
By this point life itself has become suffering for Ivan. Whether it's work or staying at home, or anything else, life has become unbearable. The sense of isolation Ivan feels is a large part of his agony. Even worse, it's not clear what Ivan can do to change anything. It's possible that his whole future looks like this (in fact, that's the way it turns out).
| Quote #5
For his excretions also special arrangements had to be made, and this was a torment to him every time – a torment from the uncleanliness, the unseemliness, and the smell, and from knowing that another person had to take part in it. (7.2-4)
As Ivan's body goes, he certainly suffers a lot of physical pain. But that's not all: he also suffers a loss of dignity. He can no longer do the things he used to, and he now depends on other people to take care of him. And taking care of him means dealing with the more disgusting aspects of Ivan's illness. This is humiliating.
| Quote #6
Once when he got up from the commode too weak to draw up his trousers, he dropped into a soft armchair and looked with horror at his bare, enfeebled thighs with the muscles so sharply marked on them. (7.6)
Ivan's physical decay is also torturous to him because he can barely recognize his own body. He has to watch himself fall apart. He's been used to a healthy body all his life, and now he's losing it quickly and becoming something he himself finds disgusting.