Ask an Eye Doctor and Get an Answer ASAP
Thank you for the question.
The skin under the eye is very thin and has loose connective tissue. Thus it has the ability to retain water quickly. However with fluid under only one eye, it is unlikly to be due to any systemic disease. You are right about a reaction from bug bite. The bite mark might be small and can get missed. Best solution is to apply ice pack to that part and take Syrup Benedryl,15 ml once. It might cause drowsiness in some hence avoid driving.
It is likely to subside in the next couple of days with the above measures.
Do let me know if you have any follow up questions.
Thank you and best wishes
Wish you a happy new year in advance.