Should I go to urgent care for a peritonsillar abscess? I made an appointment with an ENT but they can't see me until the 9th. I'm swollen and in pain

Yes but. yes this way they will start you on antibiotics, and some topical treatment until you see the specialist. you can go to the ER, it is more expensive,but if they found out that your condition urgent and required immediate surgical intervention, they can admitt you and ask for an urgent ENT consult. either way seeing somebody sooner will be better.