helo
welcome to hcm
swelling under eye could be due to number of causes. it would be helpful to know if you have any other problems such as
fever,
rash elsewhere, watering from eyes, pain in eyes, change in vision, icthing elsewhere,
muscle pain,
joint pains.
based on the other associations with your problem you would need either an ophthalmologist ( eye specialist) or a physician (internal medicine specialist).
hope this is helpful.