Eye pain/lump in one of my eyes?

So, for the past few months I've been having problems with my left eye. It occasionally hurts, sometimes when I put on make up, and more often it gets a quick, intense pain that just lasts for a few seconds. It's also has some vision problems, and is a bit blurry and weird sometimes. My doctor hasn't found anything wrong with it. I JUST noticed that there's like a pebble size lump under my left eyelid, in about the place where the intense pain has occured.. Do you think there has been something stuck in there for all these months (is that possible, with tear ducts and all?), or what else could it be?