The ebb & flow of B12 is known to be a slow and lengthy process. Any discomfort with the shots?
Yes. They sting a bit. I have found that if I push down on my skin as I'm receiving my shot (which I administer) and I inject very slowly, the sting can be mitigated.
You can get injectable B12 used for cattle. Syringes at Walmart or Amazon. Get the 1/2 inch.
I occasionally inject right below neck or into shoulder between the blades.
I have had acute hypertension and this will limber you up within seconds and your entire neck/ shoulder area just go limp and relaxed .
You cannot overdose so no worries there.
It only hurts if you reuse the needles.