You may have recurrent erosion syndrome. See an ophthalmologist.
Dr. O.
i had this a few times and no one, even hospital could see anything. till it happened and i couldnt open my eye at all. whent to hospital after 3 days and i had a small tare on my eye. got it fixed pretty pain free and quickly done
You need to see an ophthalmologist so the eye can be examined with microscope ( slit lamp ). You will not be able to see a small foreign body. Also, this could be due to some other disease process.
Dr. O.