your skylight is one of the millions that are cracked and leaking. They over torque all plastic pieces cause the workers don't understand that torquing metal to metal vs. torquing plastic to metal needs a different torque gun...real simple.
They just over caulk the outside and eventually the crack gets bigger and gets exposed to rain. Take the inside cover over the shower off to see if it is wet there. Leave it off for a while if it is wet . cover the outside skylight untill you can get it fixed. that is my guess anyways as that happened to mine.
It was a rainy few days at Algonquin Prov park...tarps kept us dry.
Wayne --Belle River (Windsor), Ontario
2013 Sunset Trail Reserve 25RB..
2015 White Chev Silverado 2500HD 4x4 (6.0 l gasser)
2003 Mountain Star 890SBRX Truck Camper