I used to be able to tickle my own feet a little bit when my skin was drier, but I can't any more. I don't have any of the symptoms in that NIH doc. Unsure if

I used to be able to tickle my own feet a little bit when my skin was drier, but I can't any more. I don't have any of the symptoms in that NIH doc. Unsure if related but I also receive no effects from morphine regardless of dosage. Nobody has been able to tell me why.