Why do i always get ulcers after i brush my teeth? like they come and wont go away til liks 2 weeks. and the pain it so bad that i cant eat

Canker sores: is very common after tooth extraction. Canker sores are the most common oral lesions. Individual ulcers typically last 1-2 weeks. The condition is idiopathic (cause is not known) recurrent aphthous ulcers is usually self-limiting. If concerned see your dentist after 10 days.

"Ulcers": May be canker sores. See your Dentist when one is active. There are medications and laser treatments that can give you comfort.