I agree with checking it out medically.
He's 14, I don't think he's too young to learn how to do the laundry. Work with him to show him how and make it clear it's not punishment, it's management. We had difficult child 3 learning how to change his bed well before 14.
Exampe - difficult child 3's mattress is old and a spring was poking through. It put a hole right through his gown and his pyjamas and into his skin. He was outraged at the spring, but then he tore his jeans sitting on his bed. I made him strip the bed and turn the mattress over. The jeans shouldn't have torn because he already knew about the problem.
Stripping the bed and turning the mattress wasn't punishment, it was the solution (short-term). The longer-term solution is to buy a new mattress, but he's got to have somewhere to sleep in the meantime.
Your son is in his teens - teen males (autistic or not) smell. So while oyu're teaching him how to do the laundry, get in a spray bottle and fill it with cheap white vinegar. When there is a potential smell problem (perspiration, urine etc) spray the item with vinegar and put it in the laundry tub. It doesn't matter if it dries again before washing day.
Then COLD wash. No more than 30 C, or you will cook the smells in.
Really bad stuff benefits from a pre-soak as well. I've had socks which needed a toffee hammer to deal with, come clean using this treatment.
Your understanding of the problem is probably very close to the true problem. But at 14, he needs to learn strategies to cope. Again, avoid any punishment connotations. After all, YOU do the washing at the moment and YOU didn't wt his bed, did you? So it's not punishment. Ad one day he will want to live independently, he needs to know how. So teach him to cook, as well. Teach him what he will need in terms of life skills. Work together if you need to, to get him to do it. It helps him wake up and learn how to tune in a bit better to what is needed around him.
Welcome to the site. Stick aorund, let us know how you get on.
Marg