After a period of times the swelling goes down. There is no pain associated. Pain often comes only with infection. You should see both your dentist and your doctor. I would go to the dentist first.
Some tumors have liquid centers and , like cysts, get bigger and smaller.
Please give us some follow-up. I have had a sore throat for almost 5 days, it goes from one side to the other side. I feel like i am fighting a virus. You need a throat culture. I keep getting these really irritating white lesions in my throat.