Thick green and yellow mucus with red in it. it looks like i sneezed out part of my brain. 2x now. what can this be? i also have a headache when i cough. and a little bit of a sore throat. can this be from a tooth abbess i had. should i be worried ?

If the discharge is from your nose (i.e. not coughed up from your chest), probably you have a sinus infection. Probably not related to your tooth abscess but can't tell without direct exam. See your doctor soon; you may need an antibiotic prescription. Good luck.

No, you did't sneeze part of your brain out. If you had an actual tooth abscess treatment requires both antibiotics and root canal or extraction. Probability is you also have URI, viral, which antibiotics don't treat, or a bacterial sinus infection if it was an upper back molar. See BOTH Dentist and Physician.