For wisdom tooth infection; if you have no fever and you can’t get to your doctor, you might try 8 oz of very warm salt water rinse hourly while awake. 1/2 tsp table salt to 8 oz water. Avoid chewing on affected side. After 24 hour, if no better, may we’d to start antibiotics.
Pus is yellow under pressure and cause inflammation and pain; it’s trapped between gum and yet-fully-exposed tooth; warm salt water shrinks gum and facilitate drainage; mechanical irritation from brushing may cause more swelling and impedes drainage. Water Pic can help irrigating the area and facilitate drainage.