Unless a doctor rules out ANY physical problems, considering this to be a magick issue is dangerous.
He may have a food allergy. Allergies can develop at any age. My daughter is allergic to sweet potatoes and one Thanksgiving someone dipped into the sweet potatoes and then into the mashed potatoes not knowing. My daughter was so itchy, she was rubbing on the walls! Mind you, she was only four, so her compulsion to itch was stronger than her pride. The poor girl was miserable for the whole day despite benedryl. Everyone has floaters and static in their vision. He may just be becoming paranoid.
He may also have fleas in his home. Fleas don't stay on people but they will bite and dash. Not everyone is allergic to fleas so they don't itch for everyone. My dog had fleas once and one got into my sock. My foot was itchy and sore for days. Bug bites can make you feel weird and sick in many ways just like any allergic reaction. Lice is another possibility since he itches on his head mostly. I've never encountered those, and I never want to.