I can relate to the experiences being part physical but also suggestive of dissociation. The part about being somewhat anesthetic to feeling and blasting your skin with forced hot water- like me , I've tried to make my body feel real to my self as derealization begins- trying to reestablish a mind-body connection when I notice that it has broken. In my past I have self-injured to try to reestablish the connection and force my body to feel real. I AM NOT RECOMMENDING the tactic! I have tried yoga but at those times I can't make my mind cooperate when the inner voices are trying to distract. Instead I might free-associate my thoughts on paper which reveal lots of different hand writing and then send the writing to my T just so my selves know they will have been heard. Every part of ourselves wants to be validated and make an impact on another human mind. It was Socrates who wisely said "Speak! That I Might See You." This is the first mandate of psychotherapy and psychoanalysis.
MHO I hope this maybe helps.
Kathy