Hi, my autistic son has started to chew his clothing and hair. He did it till 5, stopped for 3 years and is now doing it again. It makes his hair smell and if tied up he will just chew his clothes instead. I'm looking for recommendations on something else I can buy for him to chew on. So many online options I don't know what to try and what will be safe. Maybe something that clips onto clothing instead of going around his neck. What tried and tested ones have you tried for your kids?