So, my derm suggested it was an allergic reaction to a makeup product – concealer or something. But I'm really not a big makeup-wearer so I must admit I was skeptical about that. Regardless, he prescribed me to 3 days (day and night application) of Advantan Ointment "Methyprednisolone Aceponate" which has worked a miracle. I applied it at 2pm Tuesday and by 8pm that night it was remarkably better. By now, Wednesday night, it's almost completely gone.
Additionally, I might've had some luck finding out what my allergen is – linseed oil. I'm an oil painter and have started using a new linseed oil to dilute my paints. I noticed this afternoon that after painting for 1-2hrs that my eyes were redder, so I put it all away and gave it some time, and now, the redness (with the help of the cream) has died down a lot. I went back through my camera roll, and found that almost every photo I've taken of my eyes has been right after update photos of my paintings. It's just a guess, but I think now that I have this cream, I might give it a test on the weekend