Originally Posted by mrsD

When was the last time you had a chest Xray?

There could be something going on there. Another member here had SOB and they finally found an infection by an uncommon bacteria in her lungs.

Difficultly breathing can be also a sign of myasthenia gravis.
So getting a doctor's evaluation is important.

Some people have too many red blood cells...polycythemia vera.
B12 in high doses is not recommended for them...but this is rare.

So there are things you should check out with a doctor if you have SOB.

B12 will fix things that need repair due to nerve damage, etc.
But it cannot fix everything.