So I am transitioning from swimming due to water temperature to hiking up the side of a mountain at the same time I stopped injecting and went with sublingual. (Only a mile up the mountain.)
My body did adjust which is not using up my B12 or reversing out. The only symptom that seemed to get worse and stay that way was starving for air.
I figured it out yesterday. Swimming the side stroke naturally regulates my aerobic expenditure as I can only go so fast without losing form.
I was limiting the distance I hiked. Because I am doing much better treating for Transcobalmin/Lifelong B12 defiency issues what was happening is I increased my pace without increasing my distance. I was also picking my pace up in general. Hence the starving for air.
I think it was much about fear that I was going to go back to starving for air like when I treated for Intrinsic Factor issues only.