You are quite right that having something on one eyelid is not a reaction. More likely it is eczema, a local sensitivity usually no triggered by anything in particular. I recommend that you try 1% hydrocortisone twice a day on the lid. If it's eczema, it should get much better in 2-3 days. If not, let a doctor have a look. Don't use hydrocortisone constantly in that area, but a couple of days is safe, and should tell the tale.