Why did Eliezer end up in the hospitAl ? What decision did he have to make once he was there??

Eliezer's foot begins to swell because of the cold, and he has to get an operation to prevent it from being amputated. The hospital is much more bearable since there is no work and better food. His bedside neighbor, a Hungarian Jew, warns him that all the invalids will be killed with the next selection and that he should try to leave the hospital right away. Eliezer does not know whether to believe him or to suspect that he just wants Eliezer's hospital bed. After he awakes from his operation, Eliezer worries that his leg has been amputated but is afraid to ask the doctor. The doctor tells him to trust him and that he will soon be walking in a fortnight. Two days after his operation, Eliezer hears that the front is advancing to Buna, and that very day the camp is ordered evacuated. Hospital occupants will not be evacuated, however, and Eliezer worries that all invalids will be exterminated. He runs to meet his father outside, and his right foot leaves bloody marks in the snow. After some deliberation, Eliezer and his father decide to leave the hospital and be evacuated with the rest of the prisoners.