Bed wetting

My 4 year old boy has never wet the bed before. Not even when potty training. And the last two nights he has and a lot. My immediate thought is stress but honest nothing has changed in his life. I don’t think it’s a stress thing. No change in routine or life. It’s actually been a good few weeks. Google ( which is a bad source) says UTI or something medical. Has anyone experienced this or has a thoughts? I’m going to call his doctor tomorrow.