It is probobly a stye. Use a warm, wet washcloth or something similar and apply pressure on the area. Pulling the eyelids on the eye works too. I had two styes in the past. One lasted for about a week and was a pain, and the second one lasted for about 3 days. If you treat it enough, it eventually dissolves and comes out of your eye along with a lot of tears.
A stye is basically a collection of oils stuck between your eye and eyelid. In your case, it might not be a stye, but they seem to be the most common in eye-related problems.