Your roof my be new, but there could issues around flashing. If you’re in a snowy area, you could have problems with insulation, where the snow melts on the bottom layer and sits on top of the roof.

Water is going to find a way in. I had a new roof, and both of these issues. Had damage on the ceiling of the bottom floor and around some walls.

That’s just my one experience, and not as an expert. I ultimately made a couple small openings in Sheetrock around the house and monitored because the roof guy was called out 6 times for warranty and refused to come out again unless I could prove it was due to roof damage.

Hoping you get answers from a professional. That shit sucks to deal with and I’m sorry.

Wow. Are all your water pipes on this floor concentrated in that area? I'd want to open those walls; it seems like a significant amount of dampness. Best of luck!