Your condition is known as bromhydrosis, this is due to secretion from apocrine sweat gland
which not usually present at chest wall.
To control this bad odor you could try the following-
1. Avoid spicy or smelling food like onion, garlic, etc..
2. Apply deodorant spray or roll on chest several times a day.
For permanent relief you need some surgical procedure to destroy these type of sweat glands from a specialized dermatosurgery center.