It is hard to say exactly why your son feels afraid of going to the bathroom by himself now. He is only 5 years old and is still not yet capable of fully expressing himself verbally. It could be that he saw something on TV which scared him, he may have overheard a conversation about something related to children in the bathroom, or he may have heard a scary noise when going to the bathroom by himself at school.
On the other hand, 5 year old children should not be using public restrooms by themselves. A parent or older sibling should always accompany them in shared restrooms. The school's policy may be different because it is not really considered a public restroom, so you may want to ask his teacher about this.
Please give your son some time and hopefully with your love and support he will start to feel more confident to go to the bathroom by himself again. If you would like to speak directly with one of our counselors, please call or e-mail our Hotline. We also have a wonderful website for parents, full of parenting information and ideas.
We hope you continue to reach out. Best wishes to you and your son!
Boys Town National Hotline