Now that I discover my own children were also gripped by fears when they were young, I also wonder why I didn't understand this or help them more at the time. I think children decide for themselves how much parents can help them. They know our personalities and see our reactions to things all the time, and work out for themselves whether we might understand, or not. I like to think that we did help them a great deal by talking to them and setting a good example. However, we just can't protect them from everything they are exposed to.
When I was a teenager I was bullied at school, but at least once I got home I was safe. I can't imagine the pressures children are under nowadays with cyber-bullying and malicious texts, not to mention the whole pressure of having all this connectivity and being expected to use it or you'll be a social pariah. It must be awful not to get a text, email or Facebook message when you need these as an affirmation of friendship. That only highlights that everyone else is OK and you are not, just Billy No Mates. It's not like in our day when not every household had a telephone or the money to use a callbox, and you were expected to ask permission anyway so there were lots of reasons why you only saw your school mates at school or on the bus.
To answer your question CG, I think I developed my OCD rituals to cope with the things that I felt adults couldn't help with. In hindsight, and if my parents, teachers and parents' friends had all been perfect, then I could certainly have done with less of "pull yourself together" "why should you have anything to worry about?" "you're such a worry and a disappointment to everybody" "why can't you be more like so-and-so" "other people's children don't do......" "you'll end up with no friends if you carry on like this" "your teachers are complaining about you" etc. etc. In my own particular circumstances the messages were that I was a bad child. In fact I was dreamy, imaginative, creative, and lived in my own little world. I had not developed into the self-controlled and logic-driven individual that I later became! However, I suppose I worked my way out of OCD by the application of logic.
Again, in my particular circumstances, I know now that my mother was very unhappy for a number of reasons, she was extremely insecure anyway, and while she was a tremendously dedicated and caring mother she was also trying to mould her children into the people she wanted them to be. In her day, the childcare books subscribed to the 'blank slate' model - children were the product of their upbringing, so if they weren't good children it must be the parents' fault. There was tremendous pressure on me to be a good child and to please my teachers. My mother had been at boarding school from the age of 3, and her emotional survival depended on being a good girl. I really think she, and my father, believed that if I was asked to leave my school I would end up in some sort of institution. This sounds really extreme, and I was just a normal little girl, kind to animals and children, honest and truthful. But I was untidy, had unruly curly hair, inclined to daydream, extremely forgetful, only worked hard at the things that interested me, and generally didn't seem like the best material for my convent school to work with.
Sorry to ramble on, and I don't want to hijack the OP's thread. I would say, IMO, that the pressures a child is under will be partly those personal insecurities about popularity, school performance, appearance and attractiveness, what am I going to do with my life, etc. The other pressures are to do with their home circumstances. This is where parents can be a help or a hindrance. I am no expert. I have a child who began an addiction aged 15 that I was unaware of for 4 years, so I can hardly offer myself as any kind of parenting role model. She says that it would have made no difference if I had known because it was her issue, and I couldn't have helped. I don't know whether that is true, but the secrecy can't have made her any happier.
I suppose if I was the OP I would get the phrase OCD out in the open and then her son can find out some more about it for himself if he is not willing to be helped by his family at present. It is tremendously embarrassing for a child, especially a teenage child, to be seen as someone with a problem that other people have decided needs fixing. When life problems coincide with puberty the child must feel especially scared of the changes happening to their body and emotions. Everything seems to be out of control. No wonder control rituals seem to offer some respite from the emotional storms. Can you remember what it was like to be 13? I wouldn't want to go through it again.