Thanks for the query,
You have developed an allergic reaction
The cause can be varying,
It can be due to an insect bite or any thing taken orally or inhaled.
Apply a steroid lotion like fluticasone
Also take an antihistamine tablet.
If there is no response you may require oral steroids
This will give you some relief.
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.