<s>[INST] Hi, I recently had my back molars removed because they became infected. And about 2-3 weeks after my surgery I have black bruise like marks on in the back of my mouth on my inner cheeks. Also my lip is beginning to swell a little and it has a bruise like mark now. What is this? Should I see my regular PHD or a Dentist? [/INST] thanks for the query, the black bruise like marks could be because of the ecchymosis secondary to cheek biting or normal physiologic pigmentation. the swelling over the lip could be secondary to tooth infection. consult your oral physician to take radiographs and rule out the causative tooth. if i am your treating doctor i would start with a course of antibiotics and tell you to gargle with saline. i hope my answer will help you, take care. </s>