A metaphor compares things WITHOUT using like or as. similes use like or as. the first one, with "stomach swims", seems like personification,giving an object human qualities. I would go with the second one, some assume a simile to branch underneath metaphor, I'd assume. the first one isn't comparing anything, so it's probably the second choice.
I knew then I had to have a house. A real house. One I could point to. But this isn’t it. The house on Mango Street isn’t it. For the time being, Mama says. Temporary, says Papa. But I know how those things go.
