Swollen side of mouth. What is this????

[Mentat]

If frog is eating and you can monitor in present enclosure, maybe can observe there. If not, would move to hospital type enclosure where close monitoring is possible.

If it get's increasingly worse during today, might need antibiotics. Do you have a topical anti-bacterial based on silver or maybe Baytril on hand? You might need it in the next couple of days. Good luck !