First of all

I think that this is something that is common but not spoken about much.

My neighbours son at 7 wets the bed, by best friends daughter at 6 wets the bed, I have Mason in a nappy at night as we tried him without it and after 3 weeks wetting every night it's not a stress I need.

I also wet the bed for years and I can remember that I would dream about going to the toilet and wake up wet.
Maybe he is sleeping to heavily to wake up to go to the toilet.

I'm not sure about the poo part, has he been constipated and is scared to go and is holding on till he can't hold on anymore? If this is isn't the case maybe get him to a paediatrician to rule out anything physiological.

With the 3yo they can have setbacks. Mason didn't even want to sit on the toilet till he was 3 1/2. And boy IKWYM about being given advice for that one. I sent him to kinder in a pull up and it was in the first term holidays that he did a wee on the toilet. We are still getting there with poos.