Hi ,

Sometimes ulcers on tongues can happen because a kid had bitten on its tongue. Ulcers can also be caused by a virus. But stress, allergies and vitamin deficiencies can play a role as well.

Manuka Honey
Honey has antibacterial and anti-inflammatory properties and can give some relief when applied topically.

Chamomile Tea
which can be held in the mouth, swished, or applied as a wet compress (via the tea bag)

Baking Soda Rinse
A little less tasteful, but a Baking soda rinse might help as well.

Ozonated oil
Some holistic dentists use ozonated oil as a treatment. Personally, I do not have experience with this. Sesame oil seems to work as well according to this article.

Acid foods
Try for the time being to eliminate acidic foods like tomatoes, Pineapples, oranges, lemons, and limes. 

I hope this helps!

 if your daughter is having recurring episodes of ulcers/canker sores, food sensitivities if often the root cause which can reflect an inflammatory response in the mouth. Gluten is a common culprit, but it could be other foods as well (e.g. citrus, which is further aggravated by the strong acidity of its juices).

An elimination diet with structured reintroduction could be an option to help you determine the culprit.
Other potential causes include:
• SLS in toothpaste. More on this here.
• Nutrient deficiencies. • Most commonly B vitamins (e.g. B2/riboflavin, B3/niacin, B12, and/or B9/folate) as these nutrients support the protective mucosal layer of the mouth.
• Zinc – zinc lozenges are a great way to get direct, topical application
• H. Pylori, which can cause ulcers not only in the stomach and duodenum but also in the mouth.

Also eliminate any alcohol-based or other harsh mouthwash, which can disrupt the microbiome in the mouth. Oral probiotic lozenges may help support the oral microbiome, as may lactobacillus acidophilus. 
Note too that canker sores are different from other mouth sores such as cold sores, angular cheilitis, or burning mouth syndrome.
To help an existing ulcer to heal, consider the following in addition to Daniel’s suggestions above (Manuka honey, chamomile tea, baking soda rinses, eliminating spicy/acidic foods to help with healing):
• Zinc lozenges
• DGL lozenges
• Licorice extract applied topically
• There are also some homeopathic remedies for canker sores such as this, this, and this.
• Ozonated oil, which can be purchased from most holistic dentists shows a reduction in pain and faster healing.

To learn more about canker sores and potential home remedies, check out this article.