I found this great remedy in my trusty natural remedy book – “Gentle Healing Hands for Baby & Child”.
Salty Lemon Gargle
1) Combine the juice of half a lemon with one tablespoon salt in 1/2 cup warm water
2) Gargle the mixture at least 4 times a day
If you want a faster working remedy, instead of mixing with water, you could mix it with 1/2 cup sage tea.
I hope it works for you!