I agree with checking above. The vent stack is often in the immediate area of the toilet. Water could follow that down pretty much unnoticed.
I'm 99% certain that my 23b wheel wells not being properly sealed contributed to some of the floor damage in my toilet area. I'm not saying that is your problem, but if the toilet is in the general area of the wheelwheels it may be worth a close look. When I removed the wheelwell arch fancy trim I could see where the water was able to get into the flooring and under the vinyl.
Any outside running lights or water service ports are another classic water leak possibility.
Shower wall seams and fasteners have some history, but I think that your shower is separate and across the hall, so that is less likely.
Good luck. vic