Thank you for your query at DoctorSpring.com
I have seen the pictures you sent.
It looks really inflamed and if it gets worse you will need to visit the ER for prophylactic treatment.
You should clean the area with soap and water and take Levocetrizine immediately if you have one.
This will bring down the swelling and the associated redness. Since you have no idea what insect bit you, it is better to observe it for the time being. If you develop symptoms such as excessive sweating, dizziness, fever, e.t.c you may need to visit the ER. As of now cleaning the area, and levocetrizine 5 mg will be helpful.
Feel free to discuss further,