What are the signs of an infection or abscess following a temporary crown?

I had a temporary crown placed two days ago on the back molar on the right side of my mouth. The gum area directly behind the tooth have been swollen and throbbing ever since, and now going on day three there are two areas that have developed a white “patch”. It’s a holiday weekend and my dentist isn’t calling back so I’m just wondering if I should go to an urgent care for antibiotics? Just not sure if it’s healing from the trauma or becoming infected.