It seems that you may be having bullous insect toxic dermatitis
After insect bite, initially, there is erythematous lesion followed by bulla.
Ther may be itching and burning sensation.
There may be pain also. It may be use to secondary bacterial infection.
Take antibiotics with anti inflammatory drugs.
Take anti histaminics like cetirizine
If needed, steroids
in tappering dose may be taken.
Apply antibiotic cream. The lesion may heal in 2 to 3 weeks.
Keep the hand elevated to reduce oedema.
I hope you got my answer.
Dr. Ilyas Patel MD