What is the smell coming from under the house like body odor?

It is probably a dead shark. I had this problem so i went under my house and found a rotting bees nest. If you have ever been to hanmer springs in New Zealand, there are hot springs there which have a strong sulphuric smell. There are also thousands of bees there. While the bees do not cause the smell, they certainly make it worse. Look for any traces of bees under and around your house and spray contaminated area/s with water and sodium bicarbonate, which will neutralise the smell.