How can I get DH to stop picking his skin?

Try CBD oil tinctures under the tongue. Seemed to help our LO. Keep his nails short and clean.
There are many threads on this topic here on the forum. So it is fairly common.

That is bad. Sounds like a subconscious habit. Or OCD behavior. Does keeping the skin covered help? That's all I can think of.

Yes. My mom does this and the neurologist says he sees this in patients with dementia or Alzheimer’s. He said it’s not typical behavior but he sees it. In her case it is a combination of absent-minded picking and then once it is bleeding she thinks she has a skin cancer and attempts to remove it.m herself. She does this to her face, arms, and neck despite several doctors including a dermatologist telling her to stop. What seemed to help a lot was putting tight bandages on the wounds so that she couldn’t get at them. That didn’t help with her face, but I think seeing the bandages served as a reminder to her. Also applying antibiotic ointment along with the bandages seemed to help. If you bandage the wounds tightly will he tolerate that or will he remove the bandages?