It's probably just a sinus problem that'll go away in a day or two.
However, it could be something wrong with your eye, for example some sort of glaucoma-like condition is building up pressure inside the eyeball, causing the orb of the eye to expand and press against the orbital socket. If that kind of thing continues, it'll cut off blood flow to the eye. First, you'll go painfully blind as the nerve tissue dies off (optic nerve tissue is very fragile stuff), then as the tissue of the eyeball is deprived of oxygenated blood it too will die, and the orb of the eye will necrotise. At this point it will start to shrivel up again, and probably blacken. The pressure pain will ease off from the eye socket, but you'll have a brand new agony as the fibres holding the eye in place slowly rot away. This will continue until the eye falls out of the socket all together, although bear in mind that this may involve you using a sharp knife to sever the remains of the optic nerve at the rear of the eye, otherwise it'll just droop on your cheek like a rotten pickled onion on a string. Once the eye has fallen out and you've carefully cut away any remaining dead tissue, it should all clear up in a few weeks.
Of course, if any necrotic tissue remains in the socket, it could spread a gangrenous wasting throughout the surrounding tissue, which, due to the channel that the optic nerve follows, would eventually lead to bits of your brain rotting away, almost certainly leading to a short period of increasingly-pronounced insanity as your frontal lobe disintegrates before you die in spasms, being left with no control over any of your bodily functions and caked in your own fecal matter.
Whichever way it goes, time will sort things out. It usually does.