Your symptoms:
A painful lump at the edge of one eye or under your eyelid
If it’s at the edge of your lid, that pimple-like bump might be a sty. Sties are caused by an infected eyelash follicle; they can get tender and swollen and may ooze pus. Use a warm washcloth to encourage drainage; if it’s really bothersome or painful, or if it doesn’t improve with home treatment, see your eye doctor, who can prescribe an antibiotic ointment.