Had dental appt today and got cut/injury inside of mouth behind of lip. bleeding is stopped but i see a blister. does this often happen? what can i do

It happens: Your post did not explain how the injury occured or the circumstances behind it. Although every effort is made to prevent something like this from happening, it sometimes does. The bleeding has stopped, you are not swollen and not in pain. It most likely will heal without incident, like almost every other wound you may incur. Avoid hot or spicy foods while it heals and let the dentist monitor it.

Very common: Soft, non-spicy food and saltwater rinses may promote healing. Do not smoke or drink alcohol. If you need to see a doctor for your injury, call and schedule post-op appointment.