Look at the mirror with pulling your upper eyelid and lower eyelid apart and try to blink several times to see whether it will come to the corner. If you do find nothing in your eye, maybe your retinea has been scratched, which make you always feel something in your eye. However, the cornea will get healed itself within 24-48 hours. If you can't tolerate it, you'd better go to see a doctor as soon as possible. The doctor will prescrible you some eye drops to help you ease the symptom.
You can try again to check your eyes carefully. Try to pull your eyelid outward with your finger and blink several time, if there is something in your eyes, it will come to the corner of your eyes. If you still find nothing, it may caused by dry eyes or damages of cornea. I am not a eye doctor, You'd better visit eye doctor immediately to see what's really going on with your eyes.