Thank you for your question.
I am Dr Saha, I shall try my best to help you.
Swelling of the gum can come from an infection, inflammation.
Allergy can cause swelling.
Allergy can also cause a numb feeling.
Allergy is a common cause.
Besides this, among other medical cause, some deficiency state like calcium, sodium, potassium, etc, can cause numb feeling.
Hyperventilation can also be a cause of numbness.
Diabetes is another cause.
Neurological conditions needs to be excluded too
I would suggest to consult your primary doctor for examination and investigations.
He can then refer you to specialist, if necessary.
I hope this information helps.
If there’s anything else I can do, please let me know.
If you are satisfied, please rate my answer as good or excellent.