What does major kovaloff believe happen to his nose?

He believes, Madame Podtotchina used witchcraft to make his nose disappear.

Explanation:

In the story "The Nose," Major Kovaloff discovers that his nose is missing, without any explanation. He tries to find a reason for this rare occurrence, and the only thing he can think of is that the nose was stolen by Madame Alexandra Podtochina Grigorievna, a woman who wants him to marry her daughter.

adding more details about the struggle rainsford experiences as he swims to the shore