Hi, Welcome to Health care magic forum.
It appears to be an allergic reaction
to some thing, or due to a sting of the insect. The other reason may be the filarial infection, some times happen like this and flow down to the foot.
I advise you to consult a physician for diagnosis and treatment. You may need to have a mid night blood stream test for confirmation of the filariasis
, if you live in tropical area, because it is a disease of tropical area.
Take more of green leafy vegetables, pulses, sprouts,and
protein rich foods to hasten the recovery.
Wishing for a quick and complete recovery. Thank you.