Once again, let me repeat I have no medical training. The info here comes from a combination of my and others' personal experience, and from reading:
It's more complicated than "It might be a blister, so we better punch the boot".
Ask someone who recognizes blisters and bunions and other foot problems to look at your feet to see if the blisters really are blisters, and show your feet and boots to an expert pro shop, and discuss solutions with them.
Blisters are usually caused by heat from friction, caused by slippage, from too little pressure, there or elsewhere in the boot. E.g., they can come from the boot(s) being too large or not being laced tight enough.
So punching (stretching) the boot(s) may be counterproductive, because it reduces the pressure. On the other hand, if punching lets the rest of the boot firmly touch your foot, because the pressure point prevents some of the boot from firmly touching the foot. Full contact can create less slippage, that could eliminate the cause for a blister.
Pay attention to your feet when they are in the boot. Is there excess or less pressure at the point in the boot where the skin problem has occurred? Can you feel motion inside the boot when you move?
Many people with heels that are larger than the part of their feet that is in front of them need to kick the heels of their boots (with feet inside!) into the floor to force their heels firmly into the heel pocket before tightening the laces.
Other potential issues that help create blisters, like too much sweat, or an allergy to the materials in the boot or socks, or, for some people, not wearing socks, and for some people, wearing socks that are too thick. (One thin sock/foot works for most but not all people.)
Like other people have said, you now need to cover the blister with something until it heals. And if you cover it with something slippery on the outside like a Band-aid (or other brand adhesive strip), the slippage won't occur with the skin, which is good. Many people use such materials even after the blister goes away, to prevent it in the future.
Of course, if it is actually a bunion, produced by excess pressure, adding the extra material will increase that pressure, and things could get worse.
So get the expert diagnoses first.
BTW, there is an element of trial and error to getting rid of foot problems, even if you involve experts. You may have to try several things.
Good luck!
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Could someone here provide a good explanation of how one recognizes the differences between blisters, bunions, corns, callouses, and anything else vaguely similar?