Yes, he was doing it mostly at home.
He was/is more likely to mask outside the home. He is autistic as well though we didn’t know that when this started, he wasn’t diagnosed for another few years. OCD is more common in autistic people.
He was initially seen at an enuresis clinic as he was bed wetting too at that age (6). They said the daytime running to the toilet was because he wasn’t drinking enough water, even though he did drink a lot of water and even more milk, and even though I told them I thought it was anxiety based behaviour.
He later saw CAMHs who told us children don’t get OCD (they do).
A pp mentioned interoception, but he is hypo rather than hyper sensitive in this regard.
Anyway, he still has OCD as a late teen now, though in a different form. It is entrenched and very debilitating. We saw various psychologists over the years, without lasting success unfortunately. We are not in the UK and it was very difficult to find someone who specialised in autism and paediatric OCD. Many wouldn’t treat because of his autism…they weren’t trained in that area. And because autism involves repetitive behaviours anyway, it was often dismissed as that.
I would take him to a specialist psychologist or psychiatrist if you think this is anxiety based OP. Try and nip it in the bud if that is possible. With us, it got harder to treat as time went on. I would like to be able to go back in time knowing what I do now.
All that said, I am only talking about my own child and hopefully your situation will be much milder and have a much better outcome. But I’d act on what you’re seeing now. Wishing you both the very best.