What is in my eyelid?

A few weeks ago i had a small abscess in my bottom right eyelid. I'm not sure if abscess is the correct term but i dont know what else to call it. It went away after a week or two but then a week later i got one in the same eye on the top lid. And i am 100% sure it is in my eyelid, it is inside the tissue. Not on the corner, or edge it is literally inside the tissue. It seems to be attached to the inner layer of my eyelid but facing outward. (Im sorry if this sounds digusting but i want a real answer). It doesnt hurt at all I dont even know how i discovered it but i did. I cant feel it against my eye and its not irritating but i want to know what it is. It also made my top eyelid a little swollen. Not very noticeable but if you look closely you can tell. I'm not worried about it and dont think i should be but is it caused by something i did? And if it is can i prevent it? Any info would be great but preferably from an eye specialist or someone who has experienced the same thing. Thank you.