Phantom limb pain refers to pain in a part of a limb that was amputated. About 70% of people who lose a limb have it. How does it happen? The brain creates the sensation of pain in muscles, tendons, ligaments, etc. that no longer exist. Butler & Moseley, Explain Pain 22 (2d ed. 2013). It seems mild oxygen deprivation is not necessary for a person to feel pain because the brain can just flat out create it. Why would this reality apply to phantom limb pain but not TMS pain?
Instead of being preoccupied about mild oxygen deprivation, it might be more productive to focus on figuring out what emotion you are repressing and what triggered it? As for tips to keep your mind in the right place, I think that is just a matter of will. If I recall correctly, JanA has noted elsewhere that the will to accept what you need to accept and to do what you need to do to overcome TMS is easier to muster if you are desperate because nothing else you tried has worked. If my recollection is incorrect, I'll say it myself: desperation helps. So long as a person holds out hope for chemical or surgical relief, which itself is really a form of belief, sufficient desperation might be lacking.