swollen whitish betta lip

[faewind1]

i'm sorry this has to be quick i have an impatient 2 year old at my heals but i have a 5 gallon filtered tank with a maintained temp of around 78 to 80 degrees with safe water parameters (ie no ammonia etc...) i have one male betta and one african dwarf frog. i noticed just now he suddenly has a swollen lower lip and its white inside and part of the outside. does anyone have any idea what this may be? thank you!