Check your slide seals. Make sure they are 50% or more pressed together. Go on the roof and make sure the rubber flap is not folded in. You might need to spray a little water on the slide out room and make sure it doesn't pool or gather toward the seal. My first suspicion for a relatively new RV is that the leak is either traveling the wall and ceiling from a slide seal, or there's some water penetration from the trim strip that holds down the rubber roof on the slide top. (assuming water could leak through the screws).
It's just speculation, but that's what I'd be inspecting.