My medical mystery

Yesterday evening, under my eye started getting a little red. A short time later, it was red all underneath and starting to itch...it looked sorta like I had a black eye. Then, a little while after that it started swelling up. I took some pictures to send to David to see if he could figure out what was wrong. While I was uploading and cropping the pictures, it became even more swollen. I texted him and told him to call me. When I told him about it, he didn't know what was wrong. He told me take my contacts out and to take a benedryl in case it was an allergic reaction. I did, and within a short amount of time I could feel the swelling and itching getting better. I can't figure out what caused it, but it was very worrisome.

Update:
A short time ago, I noticed that my eye was feeling itchy. I went to look in the mirror, and the bottom part of the inside of my eye was really red. I took a benadryl and the itching has stopped and most of the redness is gone. My poor bottom eyelid is still a little puffy and really dark from last night.