You sweat probably smells like vinegar because you’re eating a diet rich in protein instead of carbohydrates when exercising. The body gets it’s energy from carbohydrates first, then fat and protein. When you’re exerting more energy than you have carbohydrate power for, your body taps into protein and fat stores. This can cause your sweat to smell of vinegar or ammonia. This should be remedied as your body’s protein has other jobs to worry about, and should not be a primary source of energy.