The soreness on tongue and gums may be due to-peroxide radicals released from hydrogen peroxide
I would advice you to take plenty of water and fluids.
Apply mucopain gel on the inflamed area.
Frequent ice packs has to be applied.
Avoid intake of hot/spicy foods.
If required,gastric lavage can be done.
Gargle with warm saline and chlorhexidine
Maintain oral hygiene