Should I say something or keep doing what I'm doing

Foster son still doesn't say anything but he has eaten small snacks in front if us. I still have to put his food in the fridge. And he will eat when we are gone. My husband takes him to the library to get new books so he mostly reads.

So we both noticed he was having accidents because of the order coming from his room. So when he goes to take a shower we change his sheets and say nothing. He at first didn't know we knew until we started doing that. I was wondering if we should keep doing that or actually speak to him about this. I imagine its humiliating at 15.

Edit: Idk what trauma he faced. I wasn't told. Idk what his last family did to him but it was enough to make him attempt to burn their house down. He was already sentenced to 6 months in a mental institution. I just don't want him to think we are trying to send him back.