hello and welcome to HCM forum,
i would be glad to answer your query,
i would like to inform you that the sudden swelling over the gums appeared following trauma from flossing.
sometimes,improper technique for flossing cause cuts over the gums,therefore i recommend you to avoid using the floss in the affected area for atleast 3-5 days, allow healing to happen.
kindly use proper technique for flossing to avoid floss cuts.
you can continue using a mouth wash,
you gums with dologel-ct (twice/day), apply it half an before the meals.
follow the given instructions, swelling will disappear in a few days.
i hope i answered your query,
i wish you good health.