Why are Royce's clothes wet?

I just went to get Royce dressed. We are still living out of suitcases and his was in the closet. As I pulled a pair of jeans out I noticed they were really wet. Then I smelt them and they had that ammonia urine smell. I thought to my self "wow that is weird" so I grabbed another pair and they were also wet. About half the clothes in the suitcase were wet. I was trying to figure out what happened when I remembered Luke (who was sleeping on the floor in my bedroom last night) getting up to use the bathroom . He is a hard sleeper and always really out of it when he wakes to use the bathroom. I also remembered a story James told me about his brother waking up in the middle of the night and going pee in the toy box in there room. I am pretty sure thats what happened to Royce's clothes. The other option is there is a stray animal living somewhere in the house, but probably not since it would have been stuck in the closet.