Sore throat? Swollen tonsils?

I had a really bad sore throat followed with swollen tonsils for quite a while. I went to the doctor and told me to just gargle with salt water and ive been doing that. The pain is gone, but it still seems like my tonsils are still red an inflamed. What happends now since the doc's just told me to gargle? What should I do, keep gargling? When should I stop?