how are swollen tonsils treated

Gargling often with warm salt water if your child is age 8 or older. You can make your own salt water by mixing 1 tsp (5 g) salt with 8 fl oz (240 mL) warm water.
Drinking warm or cool liquids (whichever feels better). These include tea, soup, juice, and rehydration drinks.
Eating flavored ice pops, such as Popsicles.

Taking over-the-counter pain medicines (such as acetaminophen or ibuprofen) to help relieve sore throat pain. Be safe with medicines. Read and follow all instructions on the label. If you give medicine to your baby, follow your doctor’s advice about what amount to give. Do not give aspirin to anyone younger than 20 because of its link to Reye syndrome, a serious but rare problem.
Getting plenty of rest.
Using a vaporizer or humidifier in the bedroom.
Using throat lozenges to help relieve sore throat symptoms. But lozenges should not be given to young children because of the risk of choking. Also, many lozenges contain unneeded ingredients that can be potentially harmful.