There are several potential reasons why you may experience stomach pain after brushing your teeth, including:

1. Toothpaste allergy: Some people may be allergic to certain ingredients in toothpaste, which can lead to digestive symptoms such as stomach pain. Common allergens found in toothpaste include sodium lauryl sulfate, propylene glycol, and artificial colors and flavors.
2. Digestive disorders: Stomach pain after brushing your teeth may also be a symptom of an underlying digestive disorder, such as inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS).
3. Medications: Some medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) or antibiotics, can cause stomach pain as a side effect. If you are taking these medications and experiencing stomach pain after brushing your teeth, it is important to speak with a healthcare provider.
4. Other medical conditions: Stomach pain after brushing your teeth may also be a symptom of other medical conditions, such as peptic ulcer disease or gastroesophageal reflux disease (GERD).

It is important to speak with a healthcare provider if you are experiencing persistent or severe stomach pain after brushing your teeth. They can help determine the cause of the pain and provide appropriate treatment.

In conclusion, stomach pain after brushing your teeth can be caused by a variety of factors, including an allergy to toothpaste, digestive disorders, medications, or other medical conditions. If you are experiencing persistent or severe stomach pain after brushing your teeth, it is important to speak with a healthcare provider to determine the cause and receive appropriate treatment.