Ask a Dentist. Get Answers to Your Dental Questions.
That little attachment from your gum to your lip is a little muscle and we call it a frenum. These can get damaged pretty easily from foods or getting bumped in the mouth. That could be why it's inflamed, raw, and sore, but not itchy. I don't think it's from an allergy, I think this time it's from trauma. Maybe corn on the cob, apples, chewy wings, granola bar,hard hoagey sandwich, etc can stick in front of those front teeth and damage that muscle. I see this all the time.
This usually takes 3-5 days to go away. If you rinse with warm salt water, that should help clear out your mouth of the bacteria and help the tissue heal.
Hope this helps- if so, click "accept"