Pigs won't defecate anywhere near their food and living area if they have the room to choose.
Which means that he's either in too small of a pen, or the pen hasn't been cleaned in a long time and is covered in feces.
Clean the pen. When that's done, take a stiff-bristled brush (horsehair brush...
His pen.
Don't clean the pig, clean the pen. Pigs are naturally clean animals. If he's dirty and stinky and covered in poop, it's because his pen is dirty and stinky and covered in poop.
Pigs generally don't like water, especially being forced into water.
Bathing can also cause their skin to dry out and crack.
It's normal for pigs to have a smell to them. At the most I'd take a stiff brush and just brush him down.
Are you sure it's him that smells, and not his sty?