This is a very interesting question.

I also suffer from this phantom itching sensation, on my back just over the right shoulder blade. I have been bothered by this for about 5 years. I get it when I am disturbed about something.

The itching sensation is so bad that I have to stop what I am doing and scratch it with the aid of a sharp spiky hair brush. But the relief is usually short lived.

My ordinary doctor (not my psychiatrist) says my problem is probably neurological. If you are experiencing this all over your body, you really have my sincere sympathies.

Only your psychiatrist can tell you whether your itching may be related to your illness, and I would be interested to know what he/she says.