Nerve damage after dental shot?

I worked for a UK Dentist and you did NOT have a shot in your cheek. The shots are into the gum where the roots of the teeth are.
You have an ulcer, or as an American you call it a canker sore. This might have been caused by the instrument scratching your cheek.
Use an antiseptic mouthwash 3 times a day, avoid salt, it stings ulcers and it should start to clear in a few days.

I have had pain and discomfort from the site of the injection from fillings before on several occasions. If the nerve it's self was damaged, you would have numbness, the sensation that is there after the shot is given. I have known people this happened to and it can take months for the nerve to regenerate. This is not what is happening to you. Salt water rinse might help, but it will eventually stop hurting.

Yes try salt water, but don't swish -- roll it around in your mouth/hold it up against that spot. Since you just had extractions, you're not supposed to be swishing or even sucking on a straw for several days.

This is why I keep my dentist s phone number handy

you may want to start filling out some organ donor cards.

The usual practice is to inject the local anesthetic into the back of the jaw where the nerves come into the jaw to achieve a nerve block and loss of sensation. I can only presume that the dentist must have grazed the lining of your cheek with one of the extraction tools. I would rinse your mouth regularly with a salt water solution if you feel it helps or a non alcohol based mouth wash. Its probably worth your while to give some feed back to your dentist.

Wait a week and if it doesn't go away call your dentist.