Why do I vomit saliva after brushing teeth?

You may have something like an upset or a swollen tissue in the lining of your lips. It might be due to different reasons like an allergic reaction, minor trauma, or a virus infection. Typical symptoms include soreness, redness, or pressure. To reduce the pain, put a cold bandage on it and stay away from spicy foods. Sufficient hydration can also be helpful. If the issue continues or worsens, it is better to visit the doctor. 

You might be talking about temporomandibular joint disorder (TMJ). Such a scenario can occur when the joint that attaches your jawbone to the skull gets stressed out. Among the symptoms are pain, pressure, and trouble opening your mouth. Teeth grinding, jaw clenching, or arthritis are the causes. To help, start with ice packs, keep a soft diet, exercise your jaw, and take care of the stress you experience.

It can be a hard time for one to have teeth that are not in shape. However, braces are a good treatment for this problem. Crooked teeth may be a cause of issues while eating and brushing. Braces are like small assistants who help move your teeth into a more appropriate position. 

We need to know which teeth and the location of the teeth for examining and the previous history. Your query is too short to answer